Yeah, but I seriously doubt there is any performance increase.
Sometime type the "free" command or run 'gkrellm' and you'll see that the 40 gazillion bytes of DRAM you bought because the Windows crowd think it is necessary are all in use, *BUT* than nearly all of it is used as disk buffer/cache buffers. I have only 768MB of mem on my laptop right now, but 606MB is used as "disk cache buffers" and I have a dozen services and several firefoxen and gnome terms up.
Here is the point - the /tmp directory hold a lot of files that are very important and accessed very often, like the AF_LOCAL socket files and the intermediate products of the gcc compiles and so on. It also contains a lot of cruft that you haven't accessed since the day you installed. The disk buffer/cache system is a lot smarter about keeping the most recently/often used blocks in memory than the tmpfs file system is.
It's usually a better bet to use your excess memory for disk buffer cache than to use it for tmpfs. The exception is when you have a deeply embedded system with no writable file system and a few fixed applications.