diff --git a/src/gadgets/arithmetic_extension.rs b/src/gadgets/arithmetic_extension.rs
index b53f03a6..394975cb 100644
--- a/src/gadgets/arithmetic_extension.rs
+++ b/src/gadgets/arithmetic_extension.rs
@@ -7,7 +7,7 @@ use crate::field::field_types::Field;
 use crate::gates::arithmetic::{ArithmeticExtensionGate, NUM_ARITHMETIC_OPS};
 use crate::iop::generator::{GeneratedValues, SimpleGenerator};
 use crate::iop::target::Target;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::util::bits_u64;
 
diff --git a/src/gadgets/range_check.rs b/src/gadgets/range_check.rs
index 4be8f80e..c878e799 100644
--- a/src/gadgets/range_check.rs
+++ b/src/gadgets/range_check.rs
@@ -3,7 +3,7 @@ use crate::field::field_types::Field;
 use crate::gates::base_sum::BaseSumGate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator};
 use crate::iop::target::{BoolTarget, Target};
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 
 impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
diff --git a/src/gadgets/split_base.rs b/src/gadgets/split_base.rs
index 716472f5..20bd50a2 100644
--- a/src/gadgets/split_base.rs
+++ b/src/gadgets/split_base.rs
@@ -5,7 +5,7 @@ use crate::field::field_types::Field;
 use crate::gates::base_sum::BaseSumGate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator};
 use crate::iop::target::{BoolTarget, Target};
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 
 impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
diff --git a/src/gadgets/split_join.rs b/src/gadgets/split_join.rs
index 45c87de9..fe3d724a 100644
--- a/src/gadgets/split_join.rs
+++ b/src/gadgets/split_join.rs
@@ -3,7 +3,7 @@ use crate::field::field_types::Field;
 use crate::gates::base_sum::BaseSumGate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator};
 use crate::iop::target::{BoolTarget, Target};
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::util::ceil_div_usize;
 
diff --git a/src/gates/arithmetic.rs b/src/gates/arithmetic.rs
index 12be0bc2..8bbacf3a 100644
--- a/src/gates/arithmetic.rs
+++ b/src/gates/arithmetic.rs
@@ -6,7 +6,7 @@ use crate::field::extension_field::FieldExtension;
 use crate::gates::gate::Gate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator, WitnessGenerator};
 use crate::iop::target::Target;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::vars::{EvaluationTargets, EvaluationVars, EvaluationVarsBase};
 
diff --git a/src/gates/base_sum.rs b/src/gates/base_sum.rs
index e53b72f6..641a8150 100644
--- a/src/gates/base_sum.rs
+++ b/src/gates/base_sum.rs
@@ -6,7 +6,7 @@ use crate::field::field_types::Field;
 use crate::gates::gate::Gate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator, WitnessGenerator};
 use crate::iop::target::Target;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::plonk_common::{reduce_with_powers, reduce_with_powers_ext_recursive};
 use crate::plonk::vars::{EvaluationTargets, EvaluationVars, EvaluationVarsBase};
diff --git a/src/gates/constant.rs b/src/gates/constant.rs
index eb4b5b12..894016d6 100644
--- a/src/gates/constant.rs
+++ b/src/gates/constant.rs
@@ -5,7 +5,7 @@ use crate::gates::gate::Gate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator, WitnessGenerator};
 use crate::iop::target::Target;
 use crate::iop::wire::Wire;
-use crate::iop::witness::{PartialWitness, PartitionWitness};
+use crate::iop::witness::PartitionWitness;
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::vars::{EvaluationTargets, EvaluationVars, EvaluationVarsBase};
 
diff --git a/src/gates/exponentiation.rs b/src/gates/exponentiation.rs
index e85c361e..d57c9001 100644
--- a/src/gates/exponentiation.rs
+++ b/src/gates/exponentiation.rs
@@ -7,7 +7,7 @@ use crate::gates::gate::Gate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator, WitnessGenerator};
 use crate::iop::target::Target;
 use crate::iop::wire::Wire;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::circuit_data::CircuitConfig;
 use crate::plonk::vars::{EvaluationTargets, EvaluationVars, EvaluationVarsBase};
diff --git a/src/gates/gmimc.rs b/src/gates/gmimc.rs
index 6bf868c0..837b64c2 100644
--- a/src/gates/gmimc.rs
+++ b/src/gates/gmimc.rs
@@ -8,7 +8,7 @@ use crate::hash::gmimc::gmimc_automatic_constants;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator, WitnessGenerator};
 use crate::iop::target::Target;
 use crate::iop::wire::Wire;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::vars::{EvaluationTargets, EvaluationVars, EvaluationVarsBase};
 
diff --git a/src/gates/insertion.rs b/src/gates/insertion.rs
index 91d71d2e..4c1e6fdf 100644
--- a/src/gates/insertion.rs
+++ b/src/gates/insertion.rs
@@ -9,7 +9,7 @@ use crate::gates::gate::Gate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator, WitnessGenerator};
 use crate::iop::target::Target;
 use crate::iop::wire::Wire;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::vars::{EvaluationTargets, EvaluationVars, EvaluationVarsBase};
 
diff --git a/src/gates/interpolation.rs b/src/gates/interpolation.rs
index 4eabbe31..56924742 100644
--- a/src/gates/interpolation.rs
+++ b/src/gates/interpolation.rs
@@ -11,7 +11,7 @@ use crate::gates::gate::Gate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator, WitnessGenerator};
 use crate::iop::target::Target;
 use crate::iop::wire::Wire;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::vars::{EvaluationTargets, EvaluationVars, EvaluationVarsBase};
 use crate::polynomial::polynomial::PolynomialCoeffs;
diff --git a/src/gates/random_access.rs b/src/gates/random_access.rs
index 85da3eaf..4b8c913a 100644
--- a/src/gates/random_access.rs
+++ b/src/gates/random_access.rs
@@ -8,7 +8,7 @@ use crate::gates::gate::Gate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator, WitnessGenerator};
 use crate::iop::target::Target;
 use crate::iop::wire::Wire;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::vars::{EvaluationTargets, EvaluationVars, EvaluationVarsBase};
 
diff --git a/src/gates/reducing.rs b/src/gates/reducing.rs
index 01c05306..ee3232b2 100644
--- a/src/gates/reducing.rs
+++ b/src/gates/reducing.rs
@@ -6,7 +6,7 @@ use crate::field::extension_field::FieldExtension;
 use crate::gates::gate::Gate;
 use crate::iop::generator::{GeneratedValues, SimpleGenerator, WitnessGenerator};
 use crate::iop::target::Target;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::vars::{EvaluationTargets, EvaluationVars, EvaluationVarsBase};
 
diff --git a/src/iop/generator.rs b/src/iop/generator.rs
index 8cbc35ca..f71a1826 100644
--- a/src/iop/generator.rs
+++ b/src/iop/generator.rs
@@ -1,16 +1,12 @@
-use std::collections::HashMap;
-use std::convert::{identity, TryInto};
 use std::fmt::Debug;
 
 use crate::field::extension_field::target::ExtensionTarget;
 use crate::field::extension_field::{Extendable, FieldExtension};
 use crate::field::field_types::Field;
-use crate::hash::hash_types::{HashOut, HashOutTarget, MerkleCapTarget};
-use crate::hash::merkle_tree::MerkleCap;
-use crate::iop::target::{BoolTarget, Target};
+use crate::hash::hash_types::{HashOut, HashOutTarget};
+use crate::iop::target::Target;
 use crate::iop::wire::Wire;
-use crate::iop::witness::{MatrixWitness, PartialWitness, PartitionWitness, Witness};
-use crate::plonk::permutation_argument::ForestNode;
+use crate::iop::witness::{PartitionWitness, Witness};
 use crate::timed;
 use crate::util::timing::TimingTree;
 
diff --git a/src/iop/witness.rs b/src/iop/witness.rs
index 8241c7d5..daab0df6 100644
--- a/src/iop/witness.rs
+++ b/src/iop/witness.rs
@@ -1,17 +1,13 @@
 use std::convert::TryInto;
 
-use anyhow::{ensure, Result};
-
 use crate::field::extension_field::target::ExtensionTarget;
 use crate::field::extension_field::{Extendable, FieldExtension};
 use crate::field::field_types::Field;
-use crate::gates::gate::GateInstance;
 use crate::hash::hash_types::HashOutTarget;
 use crate::hash::hash_types::{HashOut, MerkleCapTarget};
 use crate::hash::merkle_tree::MerkleCap;
 use crate::iop::target::{BoolTarget, Target};
 use crate::iop::wire::Wire;
-use crate::plonk::copy_constraint::CopyConstraint;
 use crate::plonk::permutation_argument::ForestNode;
 
 pub trait Witness<F: Field> {
diff --git a/src/plonk/circuit_builder.rs b/src/plonk/circuit_builder.rs
index b9a6ec6e..171ba9c4 100644
--- a/src/plonk/circuit_builder.rs
+++ b/src/plonk/circuit_builder.rs
@@ -19,13 +19,12 @@ use crate::hash::hashing::hash_n_to_hash;
 use crate::iop::generator::{CopyGenerator, RandomValueGenerator, WitnessGenerator};
 use crate::iop::target::{BoolTarget, Target};
 use crate::iop::wire::Wire;
-use crate::iop::witness::{PartialWitness, PartitionWitness};
+use crate::iop::witness::PartitionWitness;
 use crate::plonk::circuit_data::{
     CircuitConfig, CircuitData, CommonCircuitData, ProverCircuitData, ProverOnlyCircuitData,
     VerifierCircuitData, VerifierOnlyCircuitData,
 };
 use crate::plonk::copy_constraint::CopyConstraint;
-use crate::plonk::permutation_argument::ForestNode;
 use crate::plonk::plonk_common::PlonkPolynomials;
 use crate::polynomial::polynomial::PolynomialValues;
 use crate::util::context_tree::ContextTree;
@@ -645,12 +644,10 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
             constants_sigmas_commitment,
             sigmas: transpose_poly_values(sigma_vecs),
             subgroup,
-            copy_constraints: self.copy_constraints,
             gate_instances: self.gate_instances,
             public_inputs: self.public_inputs,
             marked_targets: self.marked_targets,
-            num_virtual_targets: self.virtual_target_index,
-            partition,
+            partition_witness: partition,
         };
 
         // The HashSet of gates will have a non-deterministic order. When converting to a Vec, we
diff --git a/src/plonk/circuit_data.rs b/src/plonk/circuit_data.rs
index 379e0d61..869b91b5 100644
--- a/src/plonk/circuit_data.rs
+++ b/src/plonk/circuit_data.rs
@@ -13,7 +13,6 @@ use crate::iop::generator::WitnessGenerator;
 use crate::iop::target::Target;
 use crate::iop::witness::{PartialWitness, PartitionWitness};
 use crate::plonk::copy_constraint::CopyConstraint;
-use crate::plonk::permutation_argument::ForestNode;
 use crate::plonk::proof::ProofWithPublicInputs;
 use crate::plonk::prover::prove;
 use crate::plonk::verifier::verify;
@@ -146,18 +145,14 @@ pub(crate) struct ProverOnlyCircuitData<F: Extendable<D>, const D: usize> {
     pub sigmas: Vec<Vec<F>>,
     /// Subgroup of order `degree`.
     pub subgroup: Vec<F>,
-    /// The circuit's copy constraints.
-    pub copy_constraints: Vec<CopyConstraint>,
     /// The concrete placement of each gate in the circuit.
     pub gate_instances: Vec<GateInstance<F, D>>,
     /// Targets to be made public.
     pub public_inputs: Vec<Target>,
     /// A vector of marked targets. The values assigned to these targets will be displayed by the prover.
     pub marked_targets: Vec<MarkedTargets<D>>,
-    /// Number of virtual targets used in the circuit.
-    pub num_virtual_targets: usize,
-
-    pub partition: PartitionWitness<F>,
+    /// Partial witness holding the copy constraints information.
+    pub partition_witness: PartitionWitness<F>,
 }
 
 /// Circuit data required by the verifier, but not the prover.
diff --git a/src/plonk/permutation_argument.rs b/src/plonk/permutation_argument.rs
index ec8f3629..9dca05c6 100644
--- a/src/plonk/permutation_argument.rs
+++ b/src/plonk/permutation_argument.rs
@@ -1,6 +1,5 @@
 use std::collections::HashMap;
 use std::fmt::Debug;
-use std::hash::Hash;
 
 use rayon::prelude::*;
 
diff --git a/src/plonk/prover.rs b/src/plonk/prover.rs
index 1a68953c..c292295c 100644
--- a/src/plonk/prover.rs
+++ b/src/plonk/prover.rs
@@ -8,11 +8,8 @@ use crate::hash::hash_types::HashOut;
 use crate::hash::hashing::hash_n_to_hash;
 use crate::iop::challenger::Challenger;
 use crate::iop::generator::generate_partial_witness;
-use crate::iop::target::Target;
-use crate::iop::wire::Wire;
-use crate::iop::witness::{MatrixWitness, PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{MatrixWitness, PartialWitness, Witness};
 use crate::plonk::circuit_data::{CommonCircuitData, ProverOnlyCircuitData};
-use crate::plonk::permutation_argument::ForestNode;
 use crate::plonk::plonk_common::PlonkPolynomials;
 use crate::plonk::plonk_common::ZeroPolyOnCoset;
 use crate::plonk::proof::{Proof, ProofWithPublicInputs};
@@ -31,12 +28,11 @@ pub(crate) fn prove<F: Extendable<D>, const D: usize>(
 ) -> Result<ProofWithPublicInputs<F, D>> {
     let mut timing = TimingTree::new("prove", Level::Debug);
     let config = &common_data.config;
-    let num_wires = config.num_wires;
     let num_challenges = config.num_challenges;
     let quotient_degree = common_data.quotient_degree();
     let degree = common_data.degree();
 
-    let mut partition_witness = prover_data.partition.clone();
+    let mut partition_witness = prover_data.partition_witness.clone();
     timed!(
         timing,
         "fill partition",
@@ -258,14 +254,12 @@ fn wires_permutation_partial_products<F: Extendable<D>, const D: usize>(
         .enumerate()
         .map(|(i, &x)| {
             let s_sigmas = &prover_data.sigmas[i];
-            let numerators = (0..common_data.config.num_routed_wires)
-                .map(|j| {
-                    let wire_value = witness.get_wire(i, j);
-                    let k_i = k_is[j];
-                    let s_id = k_i * x;
-                    wire_value + beta * s_id + gamma
-                })
-                .collect::<Vec<_>>();
+            let numerators = (0..common_data.config.num_routed_wires).map(|j| {
+                let wire_value = witness.get_wire(i, j);
+                let k_i = k_is[j];
+                let s_id = k_i * x;
+                wire_value + beta * s_id + gamma
+            });
             let denominators = (0..common_data.config.num_routed_wires)
                 .map(|j| {
                     let wire_value = witness.get_wire(i, j);
@@ -275,7 +269,6 @@ fn wires_permutation_partial_products<F: Extendable<D>, const D: usize>(
                 .collect::<Vec<_>>();
             let denominator_invs = F::batch_multiplicative_inverse(&denominators);
             let quotient_values = numerators
-                .into_iter()
                 .zip(denominator_invs)
                 .map(|(num, den_inv)| num * den_inv)
                 .collect::<Vec<_>>();
diff --git a/src/util/marking.rs b/src/util/marking.rs
index 5019511a..acbf8543 100644
--- a/src/util/marking.rs
+++ b/src/util/marking.rs
@@ -2,7 +2,7 @@ use crate::field::extension_field::target::ExtensionTarget;
 use crate::field::extension_field::Extendable;
 use crate::hash::hash_types::HashOutTarget;
 use crate::iop::target::Target;
-use crate::iop::witness::{PartialWitness, PartitionWitness, Witness};
+use crate::iop::witness::{PartitionWitness, Witness};
 
 /// Enum representing all types of targets, so that they can be marked.
 #[derive(Clone)]