OS X 10.8 Mountain Lion added a built-in speech recognition feature; you can talk to your Mac and it will type your words. It’s not great; it’s nowhere near as good as Dragon Dictate. I compared the two in a Macworld article last year.
Mavericks adds a new twist to this speech recognition feature. While the feature generally requires an internet connection – what you dictate is sent to Apple’s servers for transcription, then sent back to you, the same way Siri is on iOS devices – with Mavericks, you can use Enhanced Dictation. With this, you download a file (around 1 GB) which lets your Mac do the heavy lifting.
Unfortunately, this turns out to be quite the memory hog. Even when I’m not using it, the speech recognition process takes up nearly 1 GB of RAM on my Mac mini, which has 16 GB. That’s a lot of RAM for a process that’s not being used.
I was curious if this amount of RAM used was relative to the amount of RAM in my Mac. So I checked my MacBook Pro, which has 8 GB RAM. With Enhanced Dictation turned on, it uses just about the same amount of RAM: 980.6 MB vs 980.1 MB for the Mac mini.
If I turn off Enhanced Dictation, the standard speech recognition process only uses 17.8 MB.
So, if you use speech recognition on your Mac, be aware of the memory usage. If you only occasionally use Enhanced Dictation, think of turning it off when you aren’t using it, especially if your Mac doesn’t have a lot of RAM.