Intel Core i5 iMac enough?

[AnyOldName3]

This post is against a tonne of rules, as it's missing basically all the data we need to make a judgement on your situation... except that you mentioned Mac, and Dolphin has OSX-specific issues (mainly due to Apple insisting on writing their own drivers for 3rd party hardware, such as GPUs, and doing a shitty job of it) and performance on Macs is severely limited as OSX builds run slower than Windows and Linux builds on comparable hardware, and there's no Mac which comes with the right hardware to play all playable games.