"Something's taking too long!" 1.15.2

Singleplayer only. When loading new chunks via a horse it has reduced fps from 144fps(standing still) to 20fps on max settings which shouldn't happen considering my specs. On horseback loading chunks I only get these errors:

. With the elytra or flying, I get these type of errors:

I have tried uninstalling it and I have changed the ram from 2gb to 5gb. In other games like csgo i get the amount I should(300fps). I did a quick check but couldn't find any threads for 1.15.2 and have tried the other fixes. Also my gamerender % in f3 pie chart is 95%.