diff --git a/Cargo.toml b/Cargo.toml
index 3ebaefd9..da82d9ea 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -244,7 +244,6 @@ try_err = "deny"
 lossy_float_literal = "deny"
 let_underscore_must_use = "deny"
 iter_over_hash_type = "deny"
-impl_trait_in_params = "deny"
 get_unwrap = "deny"
 error_impl_error = "deny"
 empty_structs_with_brackets = "deny"
diff --git a/storage/blockchain/src/service/read.rs b/storage/blockchain/src/service/read.rs
index 664b35e4..a549d3a7 100644
--- a/storage/blockchain/src/service/read.rs
+++ b/storage/blockchain/src/service/read.rs
@@ -37,13 +37,24 @@ use crate::{
 };
 
 //---------------------------------------------------------------------------------------------------- init_read_service
-/// Initialize the blockchain database read service.
+/// Initialize the [`BCReadHandle`] thread-pool backed by `rayon`.
+///
+/// This spawns `threads` amount of reader threads
+/// attached to `env` and returns a handle to the pool.
+///
+/// Should be called _once_ per actual database.
+#[cold]
+#[inline(never)] // Only called once.
 pub fn init_read_service(env: Arc<ConcreteEnv>, threads: ReaderThreads) -> BCReadHandle {
     init_read_service_with_pool(env, init_thread_pool(threads))
 }
 
 /// Initialize the blockchain database read service, with a specific rayon thread-pool instead of
 /// creating a new one.
+///
+/// Should be called _once_ per actual database.
+#[cold]
+#[inline(never)] // Only called once.
 pub fn init_read_service_with_pool(env: Arc<ConcreteEnv>, pool: Arc<ThreadPool>) -> BCReadHandle {
     DatabaseReadService::new(env, pool, map_request)
 }
diff --git a/storage/service/src/lib.rs b/storage/service/src/lib.rs
index 1a2a54ca..543174a2 100644
--- a/storage/service/src/lib.rs
+++ b/storage/service/src/lib.rs
@@ -1,5 +1,3 @@
-#![allow(clippy::impl_trait_in_params)]
-
 mod reader_threads;
 mod service;
 
diff --git a/storage/service/src/reader_threads.rs b/storage/service/src/reader_threads.rs
index b4408b33..506ca392 100644
--- a/storage/service/src/reader_threads.rs
+++ b/storage/service/src/reader_threads.rs
@@ -16,7 +16,7 @@ use rayon::ThreadPool;
 use serde::{Deserialize, Serialize};
 
 //---------------------------------------------------------------------------------------------------- init_thread_pool
-
+/// Initialize the reader thread-pool backed by `rayon`.
 pub fn init_thread_pool(reader_threads: ReaderThreads) -> Arc<ThreadPool> {
     // How many reader threads to spawn?
     let reader_count = reader_threads.as_threads().get();
diff --git a/storage/service/src/service/read.rs b/storage/service/src/service/read.rs
index 00d39674..5e4be93f 100644
--- a/storage/service/src/service/read.rs
+++ b/storage/service/src/service/read.rs
@@ -14,13 +14,17 @@ use cuprate_helper::asynch::InfallibleOneshotReceiver;
 ///
 /// Uses an inner request handler and a rayon thread-pool to asynchronously handler requests.
 pub struct DatabaseReadService<Req, Res> {
-    /// The rayon thread-pool.
+    /// Handle to the custom `rayon` DB reader thread-pool.
+    ///
+    /// Requests are [`rayon::ThreadPool::spawn`]ed in this thread-pool,
+    /// and responses are returned via a channel we (the caller) provide.
     pool: Arc<ThreadPool>,
 
     /// The function used to handle request.
     inner_handler: Arc<dyn Fn(Req) -> Result<Res, RuntimeError> + Send + Sync + 'static>,
 }
 
+// deriving clone means Req & Res needs to be clone, when they don't.
 impl<Req, Res> Clone for DatabaseReadService<Req, Res> {
     fn clone(&self) -> Self {
         Self {
@@ -35,6 +39,11 @@ where
     Req: Send + 'static,
     Res: Send + 'static,
 {
+    /// Creates the [`DatabaseReadService`] with the provided backing thread-pool.
+    ///
+    /// Should be called _once_ per actual database.
+    #[cold]
+    #[inline(never)] // Only called once.
     pub fn new(
         env: Arc<ConcreteEnv>,
         pool: Arc<ThreadPool>,
diff --git a/storage/service/src/service/write.rs b/storage/service/src/service/write.rs
index 56d0a3f6..f75d6151 100644
--- a/storage/service/src/service/write.rs
+++ b/storage/service/src/service/write.rs
@@ -1,9 +1,13 @@
+use std::{
+    fmt::Debug,
+    sync::Arc,
+    task::{Context, Poll},
+};
+
+use futures::channel::oneshot;
+
 use cuprate_database::{ConcreteEnv, Env, RuntimeError};
 use cuprate_helper::asynch::InfallibleOneshotReceiver;
-use futures::channel::oneshot;
-use std::fmt::Debug;
-use std::sync::Arc;
-use std::task::{Context, Poll};
 
 //---------------------------------------------------------------------------------------------------- Constants
 /// Name of the writer thread.