Note: My pc, though it never had problems in the past, is a literal potato. (i3-2100 3.1GHz, Integrated Graphics, 8Gb RAM)
Recently I upgraded from win7 to win10. Before, I had no problems running this version of optifine at a steady 30fps. Now, however, there is a problem. I can start the game and load the main menu just fine. The problem starts when I load a world. If I'm lucky I'll get those 30fps for 5 to 6 seconds, then it drops to 0. I'm guessing that it's client side, not server, as I can move and look around (updating every 3 or 4 seconds) and so can the mobs.
Initially, I thought that it was a problem with java. But, after tinkering with it a bit, I don't know anything about java, so no front there. Other versions work fine, including: 1.8.9 (vanilla), 1.8.9 Optifine vHD U L3, and 1.14.4 (vanilla).
Say something silly, Laugh 'til it hurts, Take a risk, Sing out loud, Rock the boat, Shake things up, Flirt with disaster, Buy something frivolous, Color outside the lines, Cause a scene, Order dessert, Make waves, Get carried away, Have a great day!