Cheap'n'dirty beat detection?

I need a mediocre beat detector that isn't so heavy on the CPU.

The requirements are quite light - it's for a DJ environment with kickdrum sounds on each beat. The beats are likely all between 90bpm and 150bpm, perhaps narrower - and since I'm controlling a laser setup which also has feedback and other dynamic elements, the occasional error or glitch really won't be noticed.

(Plus, I'll have a switch to trigger by hand if it really doesn't work...)

My thought was to pass an input to lores~ and then thresh~ and perhaps some sort of logic to prevent retriggering too soon, but I'm wondering if anyone else has such a "quick and dirty" beat detector already written or knows an approach that is "known to work".

Thanks in advance, and happy new year!