Memory in Lightroom CC

How old is the machine? What kind of processor, etc. Which version of Lightroom? CC or Classic? What version (check!). Is the slowness something where it starts out fast and over time becomes slow or is it slow from the get go. Where is the slowness noticed? switching images? Doing slider adjustments? Lightroom is no speed demon and realize you are working with raw images that are computationally costly to work with.

8GB of memory is very small nowadays but your slowness is unlikely to come from Lightroom's memory use. Only if you notice a lot of swapping activity (look at the memory pressure graph in activity monitor - is it high up or somewhere in the middle) is that the problem. Programs like Lightroom will use available memory to speed up tasks. The operating system dynamically pushes part of programs out of active memory and memory use is actively managed. Safe some programming bugs, memory is usually not the cause of slowness.

Fixing slowness in Lightroom is usually a combination of having at least 16 GB of memory and a reasonably current graphics card, running the main catalog of off an SSD disk (if you run Classic), having a high quality internet connection (if you run Lightroom CC), and NOT running any antivirus software or traffic sniffing software (amazingly common that this is the issue).