diff --git a/Cargo.toml b/Cargo.toml
index d6978deb8b50cbaffd0d11dd124dccbef5758d6e..e555a0d97ebe3d1cb46ebae6cdf79c9fd3a41ca2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -43,7 +43,7 @@ crate-type = [
 ]
 
 [features]
-default = ["ffi", "session_optimization"]
+default = ["ffi"]
 ffi = [] # see src/ffi/mod.rs
 ffi_pseudo_socket_api = ["ffi", "libc", "os_socketaddr"]# see src/ffi/pseudo_socket_api.rs.
 endpoint_logging = [] # see src/macros.rs