I posted this in reply to a similar question a day or so ago. There is also a "zero cache" option which you can google to find out more but that is not recommended
"The most common cause of buffering is server overload. This is out of your control and the only alternative is to try different streams and Addons. Which Addons are causing you problems? Your broadband speed may also be a contributory factor although to be sure I would run a speed test using an app like Ookla, both wired and unwired. To some extent you can get round the buffering problem by halting a TV show or film for 5 or so minutes and then continuing. Using the xunity maintenance tool to clear Kodi cache regularly can also help.
Live sport can be a problem on the best and fastest machines, again due to the number of people using the servers. This Tuesday and Wednesday was particularly bad for football for example. You could try experimenting with the hardware acceleration settings in Kodi settings to see if this improves things.
Other things include ensuring you haveamore recent version of Kodi and Addons."
See if any of that helps