ofSleepMillis() before starting ofThread makes threading faster?

Hi, I use ofThread for one time loading stuffs(not a loop).

If I start the thread from ofApp, it takes 3~4 seconds to finish.

But if I do ofSleepMillis(500) right before starting thread in ofApp, the thread processing takes about 1 second.

So, sleeping before starting thread seems to reduce a lot of processing time.

But I don’t really understand how sleeping before starting thread can reduce processing time.

Could someone please explain why?

can you post an example?