diff --git a/Cargo.toml b/Cargo.toml
index 5d19efca3..146be05b9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -29,21 +29,25 @@ rev = "c2eb140"
 
 [dependencies.group-by]
 git = "https://github.com/Kerollmops/group-by.git"
-rev = "cab857b"
+rev = "f1f5d8f"
 
 [features]
 default = ["simd"]
 i128 = ["bincode/i128", "byteorder/i128"]
-simd = ["rocksdb/sse"]
 portable = ["rocksdb/portable"]
-nightly = []
+simd = ["rocksdb/sse"]
+nightly = ["hashbrown/nightly", "group-by/nightly"]
 
 [dev-dependencies]
 csv = "1.0"
 elapsed = "0.1"
+jemallocator = "0.1"
 quickcheck = "0.7"
 rand = "0.6"
 rand_xorshift = "0.1"
 structopt = "0.2"
 tempfile = "3.0"
 termcolor = "1.0"
+
+[profile.release]
+debug = true
diff --git a/README.md b/README.md
index e717b02aa..199affe70 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,11 @@ We made some tests on remote machines and found that we can handle with a datase
 
 Network is mesured, servers are located in amsterdam and tests are made between two different datacenters.
 
+### Notes
+
+The default Rust allocator has recently been [changed to use the system allocator](https://github.com/rust-lang/rust/pull/51241/).
+We have seen much better performances when [using jemalloc as the global allocator](https://github.com/alexcrichton/jemallocator#documentation).
+
 
 
 ## Usage and examples
diff --git a/examples/create-database.rs b/examples/create-database.rs
index 4f17d54a9..319e04acb 100644
--- a/examples/create-database.rs
+++ b/examples/create-database.rs
@@ -1,3 +1,6 @@
+#[global_allocator]
+static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
+
 use std::path::{Path, PathBuf};
 use std::error::Error;
 use std::borrow::Cow;
diff --git a/examples/query-database.rs b/examples/query-database.rs
index 4571d242e..ce64870a9 100644
--- a/examples/query-database.rs
+++ b/examples/query-database.rs
@@ -1,3 +1,6 @@
+#[global_allocator]
+static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
+
 use std::collections::btree_map::{BTreeMap, Entry};
 use std::iter::FromIterator;
 use std::io::{self, Write};