I have developed a chat site which uses reverse-ajax/COMET with php backend and works pretty well, but when I run a page in two parallel tabs of the same browser, the response slows down because the 2nd tab waits for the 1st tab to finish its execution and then the 1st tab waits for the 2nd. As a result, the site really slows down.
So PHP doesn't support simultaneous execution. How do I fix this problem?