I can only confirm what @SteveBuikhuizen said: regardless of the settings mm_compile_with_tooling_api, the save in MavensMate keeps being slow. I tried it on Mac and Windows and in different versions. My performance is constantly about 14 seconds.
Using ToolingAPI, the save-time should be between 3 - 5 seconds. I have implemented a native and free IDE CodeFusion (http://www.elastify.eu/apps/CodeFusion), which uses ToolingAPI from within APEX and from Germany my typical speed is about 3.7 seconds. Switching to MetadataAPI (CodeFusion supports both Meta and Tooling), it ends up with about 8 seconds. Again the 8 seconds I got with older versions of the eclypse plugin and v31 brings me about 4 seconds.
I totally agree, that save time is crucial. Not one single second is to waste, since it sums up during a work-day and slow saves also bring you in a bad mood - which is not good for creativity.
After implementing a save-method on my own, I see one thing which can really could be done differently. Either using ToolingAPI or MetadataAPI the call will be made asynchronously. That means you have to poll frequently, to get the current status of the async call. Now you have two choices: either you poll as fast as you can, which leads to a high local resource usage or you do it in slower intervals and waste less power for polling - but of course may get the completion later as you could.
You can compare that also to www.aside.io which does something similar from heroku with a comparable performance.
I'm also in contact with some guys from Mavens and I will forward this link to them an maybe they have an idea. Would really love to see MavensMate save as fast as possible.