If doing a small amount of arithmetic and keeping 4 bytes (or less) additional memory per client is "a lot of time and space", you may need to rethink your prio

If doing a small amount of arithmetic and keeping 4 bytes (or less) additional memory per client is "a lot of time and space", you may need to rethink your priorities. It is very, very unusual for any kind of request to anything to take a time within many orders of magnitude of how long exponential averaging will take. The difference between a GCRA implementation and complex multi-exponential average will be nanoseconds.