Document automatic CPU/IO-concurrency

doc/047_tuning_backup_parameters.rst

@@ -30,6 +30,15 @@ to increase the number of connections. Please be aware that this increases the r
 consumption of restic and that a too high connection count *will degrade performace*.
 
 
+CPU Usage
+=========
+
+By default, restic uses all available CPU cores. You can set the environment variable
+`GOMAXPROCS` to limit the number of used CPU cores. For example to use a single CPU core,
+use `GOMAXPROCS=1`. Limiting the number of usable CPU cores, can slightly reduce the memory
+usage of restic.
+
+
 Compression
 ===========