diff --git a/.github/workflows/cbench.yml b/.github/workflows/cbench.yml
index 641fe071bbe..cb30ed6e90e 100644
--- a/.github/workflows/cbench.yml
+++ b/.github/workflows/cbench.yml
@@ -13,11 +13,13 @@ on:
   # pull request.
   pull_request_target:
 
+env:
+  RUSTFLAGS: "--cfg tokio_unstable"
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: true
 
-
 jobs:
   tests:
     name: Benchmark
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d667aa84643..c4b4823df0d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,7 +16,7 @@ env:
   QW_TEST_DATABASE_URL: postgres://quickwit-dev:quickwit-dev@localhost:5432/quickwit-metastore-dev
   RUST_BACKTRACE: 1
   RUSTDOCFLAGS: -Dwarnings -Arustdoc::private_intra_doc_links
-  RUSTFLAGS: -Dwarnings
+  RUSTFLAGS: "--cfg tokio_unstable -Dwarnings"
 
 # Ensures that we cancel running jobs for the same PR / same workflow.
 concurrency:
diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index 530d4e2bbde..11bf4da86c7 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -21,6 +21,7 @@ env:
   QW_S3_ENDPOINT: "http://localhost:4566" # Services are exposed as localhost because we are not running coverage in a container.
   QW_S3_FORCE_PATH_STYLE_ACCESS: 1
   QW_TEST_DATABASE_URL: postgres://quickwit-dev:quickwit-dev@localhost:5432/quickwit-metastore-dev
+  RUSTFLAGS: "--cfg tokio_unstable"
 
 jobs:
   test:
diff --git a/Dockerfile b/Dockerfile
index 796c6a421a1..7fab6042abd 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -38,6 +38,7 @@ COPY --from=ui-builder /quickwit/quickwit-ui/build /quickwit/quickwit-ui/build
 
 WORKDIR /quickwit
 
+ENV RUSTFLAGS="--cfg tokio_unstable"
 RUN echo "Building workspace with feature(s) '$CARGO_FEATURES' and profile '$CARGO_PROFILE'" \
     && cargo build \
         -p quickwit-cli \
diff --git a/quickwit/.cargo/config.toml b/quickwit/.cargo/config.toml
new file mode 100644
index 00000000000..bff29e6e175
--- /dev/null
+++ b/quickwit/.cargo/config.toml
@@ -0,0 +1,2 @@
+[build]
+rustflags = ["--cfg", "tokio_unstable"]
diff --git a/quickwit/quickwit-common/src/runtimes.rs b/quickwit/quickwit-common/src/runtimes.rs
index 42435ce6662..fa7a4486e43 100644
--- a/quickwit/quickwit-common/src/runtimes.rs
+++ b/quickwit/quickwit-common/src/runtimes.rs
@@ -83,8 +83,14 @@ impl Default for RuntimesConfig {
 }
 
 fn start_runtimes(config: RuntimesConfig) -> HashMap<RuntimeType, Runtime> {
+    let disable_lifo_slot: bool = crate::get_from_env("QW_DISABLE_TOKIO_LIFO_SLOT", true);
+
     let mut runtimes = HashMap::default();
-    let blocking_runtime = tokio::runtime::Builder::new_multi_thread()
+    let mut blocking_runtime_builder = tokio::runtime::Builder::new_multi_thread();
+    if disable_lifo_slot {
+        blocking_runtime_builder.disable_lifo_slot();
+    }
+    let blocking_runtime = blocking_runtime_builder
         .worker_threads(config.num_threads_blocking)
         .thread_name_fn(|| {
             static ATOMIC_ID: AtomicUsize = AtomicUsize::new(0);
diff --git a/quickwit/quickwit-serve/src/lib.rs b/quickwit/quickwit-serve/src/lib.rs
index 5e92984328c..9f0e31d28dd 100644
--- a/quickwit/quickwit-serve/src/lib.rs
+++ b/quickwit/quickwit-serve/src/lib.rs
@@ -143,17 +143,10 @@ pub fn do_nothing_env_filter_reload_fn() -> EnvFilterReloadFn {
 }
 
 fn get_metastore_client_max_concurrency() -> usize {
-    std::env::var(METASTORE_CLIENT_MAX_CONCURRENCY_ENV_KEY).ok()
-        .and_then(|metastore_client_max_concurrency_str| {
-            if let Ok(metastore_client_max_concurrency) = metastore_client_max_concurrency_str.parse::<usize>() {
-                info!("overriding max concurrent metastore requests to {metastore_client_max_concurrency}");
-                Some(metastore_client_max_concurrency)
-            } else {
-                error!("failed to parse environment variable `{METASTORE_CLIENT_MAX_CONCURRENCY_ENV_KEY}={metastore_client_max_concurrency_str}`");
-                None
-            }
-        })
-        .unwrap_or(DEFAULT_METASTORE_CLIENT_MAX_CONCURRENCY)
+    quickwit_common::get_from_env(
+        METASTORE_CLIENT_MAX_CONCURRENCY_ENV_KEY,
+        DEFAULT_METASTORE_CLIENT_MAX_CONCURRENCY,
+    )
 }
 
 static CP_GRPC_CLIENT_METRICS_LAYER: Lazy<GrpcMetricsLayer> =
diff --git a/quickwit/quickwit-storage/src/object_storage/s3_compatible_storage.rs b/quickwit/quickwit-storage/src/object_storage/s3_compatible_storage.rs
index f43e2a4ae42..3f912799a53 100644
--- a/quickwit/quickwit-storage/src/object_storage/s3_compatible_storage.rs
+++ b/quickwit/quickwit-storage/src/object_storage/s3_compatible_storage.rs
@@ -22,7 +22,7 @@ use std::ops::Range;
 use std::path::{Path, PathBuf};
 use std::pin::Pin;
 use std::task::{Context, Poll};
-use std::{env, fmt, io};
+use std::{fmt, io};
 
 use anyhow::{anyhow, Context as AnyhhowContext};
 use async_trait::async_trait;
@@ -59,11 +59,7 @@ use crate::{
 /// Semaphore to limit the number of concurent requests to the object store. Some object stores
 /// (R2, SeaweedFs...) return errors when too many concurrent requests are emitted.
 static REQUEST_SEMAPHORE: Lazy<Semaphore> = Lazy::new(|| {
-    let num_permits: usize = env::var("QW_S3_MAX_CONCURRENCY")
-        .as_deref()
-        .unwrap_or("10000")
-        .parse()
-        .expect("QW_S3_MAX_CONCURRENCY value should be a number.");
+    let num_permits: usize = quickwit_common::get_from_env("QW_S3_MAX_CONCURRENCY", 10_000usize);
     Semaphore::new(num_permits)
 });