diff --git a/lib/lambda_ethereum_consensus/validator/duties.ex b/lib/lambda_ethereum_consensus/validator/duties.ex
index 9adc6003f..5a4a6d9aa 100644
--- a/lib/lambda_ethereum_consensus/validator/duties.ex
+++ b/lib/lambda_ethereum_consensus/validator/duties.ex
@@ -13,6 +13,8 @@ defmodule LambdaEthereumConsensus.Validator.Duties do
 
   @type attester_duty :: %{
           attested?: boolean(),
+          # should_aggregate? is used to check if aggregation is needed for this attestation.
+          # and also to avoid double aggregation.
           should_aggregate?: boolean(),
           selection_proof: Bls.signature(),
           signing_domain: Types.domain(),
@@ -58,7 +60,11 @@ defmodule LambdaEthereumConsensus.Validator.Duties do
 
     for {epoch, slot} <- epochs_and_start_slots, reduce: duties_map do
       duties_map ->
-        beacon = Validator.fetch_target_state_and_go_to_slot(slot, head_root)
+        beacon = Validator.fetch_target_state_and_go_to_slot(epoch, slot, head_root)
+        # If committees are not already calculated for the epoch, this is way faster than
+        # calculating them on the fly.
+        Accessors.maybe_prefetch_committees(beacon, epoch)
+
         last_epoch = Map.keys(duties_map) |> Enum.max(fn -> 0 end)
 
         {time_p, new_proposers} =
@@ -262,6 +268,7 @@ defmodule LambdaEthereumConsensus.Validator.Duties do
   def attested(duty), do: Map.put(duty, :attested?, true)
 
   @spec aggregated(attester_duty()) :: attester_duty()
+  # should_aggregate? is set to false to avoid double aggregation.
   def aggregated(duty), do: Map.put(duty, :should_aggregate?, false)
 
   @spec sync_committee_broadcasted(sync_committee_duty(), Types.slot()) :: sync_committee_duty()
diff --git a/lib/lambda_ethereum_consensus/validator/validator.ex b/lib/lambda_ethereum_consensus/validator/validator.ex
index 60611b503..c83fe858c 100644
--- a/lib/lambda_ethereum_consensus/validator/validator.ex
+++ b/lib/lambda_ethereum_consensus/validator/validator.ex
@@ -38,26 +38,10 @@ defmodule LambdaEthereumConsensus.Validator do
 
   @spec new(Keystore.t(), Types.slot(), Types.root()) :: t()
   def new(keystore, head_slot, head_root) do
-    beacon = fetch_target_state_and_go_to_slot(head_slot, head_root)
+    epoch = Misc.compute_epoch_at_slot(head_slot)
+    beacon = fetch_target_state_and_go_to_slot(epoch, head_slot, head_root)
 
-    state = %__MODULE__{
-      index: nil,
-      keystore: keystore,
-      payload_builder: nil
-    }
-
-    case fetch_validator_index(beacon, state.keystore.pubkey) do
-      nil ->
-        Logger.warning(
-          "[Validator] Public key #{state.keystore.pubkey} not found in the validator set"
-        )
-
-        state
-
-      validator_index ->
-        log_debug(validator_index, "Setup completed")
-        %{state | index: validator_index}
-    end
+    new(keystore, beacon)
   end
 
   @spec new(Keystore.t(), Types.BeaconState.t()) :: t()
@@ -85,11 +69,9 @@ defmodule LambdaEthereumConsensus.Validator do
   ##########################
   # Target State
 
-  @spec fetch_target_state_and_go_to_slot(Types.slot(), Types.root()) ::
+  @spec fetch_target_state_and_go_to_slot(Types.epoch(), Types.slot(), Types.root()) ::
           Types.BeaconState.t()
-  def fetch_target_state_and_go_to_slot(slot, root) do
-    epoch = Misc.compute_epoch_at_slot(slot)
-
+  def fetch_target_state_and_go_to_slot(epoch, slot, root) do
     epoch |> fetch_target_state(root) |> go_to_slot(slot)
   end
 
diff --git a/lib/lambda_ethereum_consensus/validator/validator_set.ex b/lib/lambda_ethereum_consensus/validator/validator_set.ex
index 3f635456b..1fb73e5d1 100644
--- a/lib/lambda_ethereum_consensus/validator/validator_set.ex
+++ b/lib/lambda_ethereum_consensus/validator/validator_set.ex
@@ -5,7 +5,7 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
   simplify the delegation of work.
   """
 
-  defstruct head_root: nil, duties: %{}, validators: []
+  defstruct head_root: nil, duties: %{}, validators: %{}
 
   require Logger
 
@@ -54,10 +54,11 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
   defp setup_validators(slot, head_root, keystore_dir, keystore_pass_dir) do
     validator_keystores = decode_validator_keystores(keystore_dir, keystore_pass_dir)
     epoch = Misc.compute_epoch_at_slot(slot)
+    beacon = Validator.fetch_target_state_and_go_to_slot(epoch, slot, head_root)
 
     validators =
       Map.new(validator_keystores, fn keystore ->
-        validator = Validator.new(keystore, slot, head_root)
+        validator = Validator.new(keystore, beacon)
         {validator.index, validator}
       end)
 
@@ -71,6 +72,9 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
   Notify all validators of a new head.
   """
   @spec notify_head(t(), Types.slot(), Types.root()) :: t()
+  def notify_head(%{validators: validators} = state, _slot, _head_root) when validators == %{},
+    do: state
+
   def notify_head(set, slot, head_root) do
     Logger.debug("[ValidatorSet] New Head", root: head_root, slot: slot)
     epoch = Misc.compute_epoch_at_slot(slot)
@@ -78,8 +82,8 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
     # TODO: this doesn't take into account reorgs
     set
     |> update_state(epoch, slot, head_root)
-    |> attests(epoch, slot, head_root)
-    |> build_payload(slot + 1, head_root)
+    |> maybe_attests(epoch, slot, head_root)
+    |> maybe_build_payload(slot + 1, head_root)
     |> sync_committee_broadcasts(epoch, slot, head_root)
   end
 
@@ -87,6 +91,9 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
   Notify all validators of a new tick.
   """
   @spec notify_tick(t(), tuple()) :: t()
+  def notify_tick(%{validators: validators} = state, _slot_data) when validators == %{},
+    do: state
+
   def notify_tick(%{head_root: head_root} = set, {slot, third} = slot_data) do
     Logger.debug("[ValidatorSet] Tick #{inspect(third)}", root: head_root, slot: slot)
     epoch = Misc.compute_epoch_at_slot(slot)
@@ -97,18 +104,18 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
   end
 
   defp process_tick(%{head_root: head_root} = set, epoch, {slot, :first_third}) do
-    propose(set, epoch, slot, head_root)
+    maybe_propose(set, epoch, slot, head_root)
   end
 
   defp process_tick(%{head_root: head_root} = set, epoch, {slot, :second_third}) do
     set
-    |> attests(epoch, slot, head_root)
-    |> build_payload(slot + 1, head_root)
+    |> maybe_attests(epoch, slot, head_root)
+    |> maybe_build_payload(slot + 1, head_root)
     |> sync_committee_broadcasts(epoch, slot, head_root)
   end
 
   defp process_tick(set, epoch, {slot, :last_third}) do
-    publish_aggregates(set, epoch, slot)
+    maybe_publish_aggregates(set, epoch, slot)
   end
 
   ##############################
@@ -148,7 +155,7 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
   ##############################
   # Block proposal
 
-  defp build_payload(%{validators: validators} = set, slot, head_root) do
+  defp maybe_build_payload(%{validators: validators} = set, slot, head_root) do
     # We calculate payloads from a previous slot, we need to recompute the epoch
     epoch = Misc.compute_epoch_at_slot(slot)
 
@@ -163,7 +170,7 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
     end
   end
 
-  defp propose(%{validators: validators} = set, epoch, slot, head_root) do
+  defp maybe_propose(%{validators: validators} = set, epoch, slot, head_root) do
     case Duties.current_proposer(set.duties, epoch, slot) do
       nil ->
         set
@@ -203,7 +210,7 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
   ##############################
   # Attestation
 
-  defp attests(set, epoch, slot, head_root) do
+  defp maybe_attests(set, epoch, slot, head_root) do
     case Duties.current_attesters(set.duties, epoch, slot) do
       [] ->
         set
@@ -215,7 +222,7 @@ defmodule LambdaEthereumConsensus.ValidatorSet do
     end
   end
 
-  defp publish_aggregates(set, epoch, slot) do
+  defp maybe_publish_aggregates(set, epoch, slot) do
     case Duties.current_aggregators(set.duties, epoch, slot) do
       [] ->
         set