Ramdisks (and ramfs) are a mixed blessing.

Whatever RAM you dedicate to the ramdisk, you are consuming from the pool. Usually, an operating system will use whatever is in the pool as disk buffers. So you're trading one kind of performance booster for another performance booster.

Also, as bluto brought up, a ramfs dies when the power goes out. Journals won't save a ramdisk.

However, if you're comparing ramfs vs nfs or a filesystem on a journaled laptop hard drive, and you are using the ramfs only for specific applications that need tons of write operations, and you don't mind the lack of safety, I'd say you could see some real benefit.