diff --git a/config/default.toml b/config/default.toml
index d022f00c..55c77906 100644
--- a/config/default.toml
+++ b/config/default.toml
@@ -28,6 +28,8 @@ salt = "asdl;kjfhjawehfpa;osdkjasdvjaksndfpoanjdfainsdfaijdsfajlkjdsaf;ajsdfwero
 # garbage collection period to manage mCaptcha system
 # leave untouched if you don't know what you are doing
 gc = 30
+runners = 4
+queue_length = 2000
 enable_stats = true
 
 [captcha.default_difficulty_strategy]
diff --git a/src/settings.rs b/src/settings.rs
index d85ed861..e2a715ae 100644
--- a/src/settings.rs
+++ b/src/settings.rs
@@ -37,6 +37,8 @@ pub struct Server {
 pub struct Captcha {
     pub salt: String,
     pub gc: u64,
+    pub runners: Option<usize>,
+    pub queue_length: usize,
     pub enable_stats: bool,
     pub default_difficulty_strategy: DefaultDifficultyStrategy,
 }