Things to do in safe mode on Mac OS X
Within the power user community there's a certain mythology attached to booting into safe mode on OS X. For instance, some people recommend it as a first step should your Mac encounter absolutely any kind of problem. This is probably effective because the caches are cleared by safe mode, and these can become corrupted, although you can clean caches on demand in normal mode using apps like Onyx.
Do bear in mind that cleaning the caches using either method may make for a slower Mac in the first few reboots after it's undertaken -- after all, the whole purpose of caches is to make your Mac faster.
Some people use safe mode to uninstall apps that otherwise prove "sticky" -- that is to say, they're impossible to get rid of in normal operating mode because they're tied to a system service that won't terminate. In safe mode all non-essential services aren't loaded, overcoming this hurdle.
Things not to do in safe mode on OS X
Don't try and do actual work in safe mode. Some apps simply won't work and the whole system will be slow and unresponsive. However, for problem solving there's little doubt that safe mode has its uses.
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