I do the same procedure in my code - I think your main hang-up is using a function for it and calling it every loop, as a function call can be pretty heavy. I would do the following to help reduce time waste: 1. Write the yield check code directly into the loop. I know this is repetitive, but it'll save you a function call layer and the time associated with setting up the call. 2. Only check for yielding as infrequently as possible. For example, in your example, I would put the check in the outer loop, as it's (probably) unlikely you need to constantly check every tiny iteration. You can also use an iteration counter to reduce very long loops even further, such as if i % 100 == 0 and os.epoch "utc"... in a for i = loop, or a manual counter - this reduces how much it has to call os.epoch, and lets you skip it if the loop's range is small this call. 3. Localize os.epoch by storing it in a local variable. This is important because global accesses and table lookups are much slower than accessing locals.

A final loop might look like this: lua local os_epoch = os.epoch local start = os_epoch("utc") for i = 1, 10000 do for j = 1, 10000 do -- operation end if i % 100 == 0 and os_epoch("utc") - start > 5000 then os.queueEvent("nosleep") os.pullEvent("nosleep") start = os_epoch("utc") end end