Really good advice and this makes a *huge* difference in playback. This, on its own, might fix everything.
Also, you can easily investigate your existing computer to see if it is capable of accepting additional RAM memory modules, or if it will accept higher capacity memory modules in place of what is there now. Your computer should tell you how much memory it has. If you look up by model number you can find what the maximum memory capacity is.
A fairly inexpensive memory upgrade for your computer might be all that you need to make a bid difference. In most cases it is as simple as removing the cover from the computer and snapping in a new or additional memory module.
Beware of two simple issues if you do this upgrade-- 1) purchase the correct memory for your specific computer, and 2) be careful with static electricity. Memory "chips" and modules are static electricity sensitive. Even walking across a carpet can create static electricity harmful to memory modules. You can easily look up some simple precautions to make sure your memory upgrade is a success. A real simple thing is make sure you are well grounded when opening a computer or memory module package.