You should really never run a game or anything else that is *consistently* CPU and memory intensive. But applications that are not constantly using the CPU should be fine. Photoshop uses lots of memory, but with 8GB you should have plenty, and it does not actually use CPU that much most of the time. So it should not slow down rendering too much.
If you do want to use other demanding applications, you can limit the number of threads/CPU cores TG2 uses. You can set this in two places, in the Preferences (which sets a permanent default), or in the Renderer Advanced tab. It's important to remember, though, that if you want to limit the maximum number of threads used (in other words you want it to use no more than 1 thread), then you should set *maximum* threads, not *minimum*. Minimum threads is useful only when TG2 does not properly detect the number of CPUs/cores you have, and you can use it to override the detected setting to fully use your CPU.
Also keep in mind that using your OS task manager to limit TG2 to only one CPU/core is very inefficient and will further slow render time even beyond limiting in TG2 to 1 thread. This is because TG2 will still try to use 2 (or more, depending on your settings) render threads, but will only have the resources of a single CPU/core, so each thread has to trade-off and it causes delay due to this switching.
Bottom line, you can do a lot while TG2 is rendering, just keep it reasonable, unless you have a quad core in which case you can strike a good balance by setting max threads to 2 and using the other 2 for other apps. You could even potentially run a not too demanding game this way.
- Oshyan