Raspberry Pi3 with Kodi runs very very slowly

My rPI3 runs very slowly with Kodi on it. I installed Kodi in March 2018 through LibreELEC. Kodi is at its latest version. Any suggestion? 1. The bootup time is fairly fast; it boots up in less than a minute which is a pleasant time for me. 2. Kodi interface is unbearable instead. Whenever I click any option it honestly takes 1 minute to load to the next page. If I need to browse for movies (I use the Midian add-on), every time I need to change a page it takes at least minute. If I select a certain movie to play the Raspberry Pi3 can take from 5 to 10 minutes, but lately it has failed to load it and freezes the complete system.  In the end for this reason I stopped using it. 3. The micro SD card I use is 16 GB Kingston, (SDC4 / 16 GB, 4 years old I suppose). 4. My source power is the official Raspberry power supply bought in March 2018.