Trying to find which is the "fastest" can only be done by identical experiments:
- You write a piece of code in all languages, with the SAME source (input) and objective (output).
- Make this in a repeat loop (for/next) to multiply the length.
- Start a timer at the beginning of the program,
- Stop it when the program has completed its work.
- Get the total time.
- Compare performances with the other languages.
It seems evident to say this, but EACH language has its own fast and slow processes, and finding the "fastest" is really a question of WHAT you are doing!
You also have to take care of each CALL you make:
In PhP, two or three similar functions would give you the same answer, but some take longer to execute (sometimes 20 times longer!) By just using a different function, you can make your code much faster!
Finally, it also depends on your server. Should your server be running Windows, you WILL BE SLOW, at least 15 times slower than Unix/Linux based servers... But, again, depends on the objective: what is 10ms delay compared to 150ms? Not much! Do this 1000 times, that is 10 sec compared to 2.5 minutes: this becomes important.
By experience, I would say PhP, but, again, it greatly depends on the application. (PhP has a lot of functions to convert/decode PDF files - an advantage, but some of the functions are slow).
By experience, ASP, JSP, javascript are sloooooow.
By experience, Compiled Java (NOT javascript) is usually pretty fast.
Trial and error is the best (and only real) advice I can give.