Somehow the thread seems to have wandered from 'Mastering' to 'Mixing'.

In the true sense, mastering is done after the mixing is complete.

There are many lightweight EQs, compressors and reverbs out there for mixing.
Ozone was meant for mastering (one instance in the final chain), and it does it's job very well.
FWIW, the Reaper EQ and compressor are nice lightweight VST FX for individual track use (and are freely available via ReaPlugs even if you don't yet have Reaper).
https://www.reaper.fm/reaplugs/

I've caught myself starting to run multiple instances of Ozone on various tracks, then later realized the error of my ways. Not due to CPU resources, but rather because I really shouldn't be processing those tracks that much at this point.
EQ, multiband compression, enhancer, limiter, spacial, reverb .. that's a lot to try to get right on a given track, and can be deceiving for a mix. You may get the track to sound awesome, but then fight with the rest of the mix, and leave no room for mastering.
I try to keep it more simpler during mixing..

For reverb I usually try to use a buss to keep everything in the same room (sharing a reverb), and the final EQ, multiband compression and limiting is usually saved for later once the mix is done.

Make your sound your own!
.. I do not work here, but the benefits are still awesome