Your system, overall, can run somewhat faster because any "extra" memory on linux and many other OS's can be used as cache-memory for your disk. I.e. every time you access your disk it will read the stuff you used into memory. If you have enough memory, eventually all of your frequently used programs will be sitting in memory waiting to be used. At any time, if a program needs more memory than is immediately available, the OS will let go of cache memory -- usually the stuff that was accessed the longest time ago. It happens automatically.
Example - my server usually doesn't need more than 10-15GB to run all its programs, and the rest of the memory ~70+GB, gradually** fills up with
cached data from the file system, so if I use any of the same things from disk, it can save time by using the memory copy. But if I run a prog needing 50G, the OS will immediately free up however much I need to run the program, as running programs usually have memory priority over file system cache.
It's not guaranteed to make any single thing faster, because whatever files you access may not be in memory when you need them, but its one of those "on the average" type things.
Note: Windows does caching as well, but marks it as 'free' --- but reclaimable if the OS can use what is in the memory (file system data, for example).
As for how much speedup you'll see -- it depends on how often your usage will fetch things from ram vs. disk.
**-- above I said "gradually" -- my linux system is usually up for weeks at a time, so stuff gradually is read into memory over the time it is up. Currently been up for 29 days.
If you turn your computer off every night or it's a portable, then you are not as likely to benefit by file data being cached in memory.