Bukkit

What steps will reproduce the problem?
1. Install the plugin
2. Use it ...
3. Damn stupid form.

What is the expected output? What do you see instead?
The expected output is a clean gameplay, like before. But since v4, on every lap/race ending, there seems to be lags

What version of the product are you using?
uCarsRace v3 - Release : no lag
uCarsRace v4 - Release : lag
This on Craftbukkit, Spigot ... version 1.7.5 and below

Do you have an error log of what happened?
No, sorry. But from the few digging I've done, looks like there are Thread.sleep(xx) at some places, and I don't know if they play well with Bukkit :-)

Please provide any additional information below.
PS: you don't commit a lot, you should so we can keep track of lagging commits ... Thanks :-)

Thanks in advance :-)