(i'm not mother tongue)hi to all,
i have been having this issue for 2 years, since 1.9 version.
pratically when i try to play minecraft to the version 1.8.9 or previous, Minecraft work well, with any kind of problem. When i try to play version after 1.9 (1.9 too), my fps are reduced to 1/2. Where? In all the worlds single and multi players and on login screen (minecraft realms, option...). A strange things, if i press "esc" when i'm playng in a world, my fps will incrase to 60/70/80. I don't remember if this is linked with my update in Windows 10, but i don't think so.
i tried everything, updated driver, updated java, reinstalled Minecraft (a lot of times), sought long hours on internet, but nothing.
Something that might help:

an error i've found on Minecraft 1.8 (that works):

If on Windows, make sure to provide all of the necessary dll's as specified in the twitchsdk README. Also, make sure to set the PATH environment variable to point to the directory containing the dll's.
<log4j:Event logger="bsu" timestamp="1495285146818" level="ERROR" thread="Client thread">
<log4j:Message><![CDATA[Couldn't initialize twitch stream]]></log4j:Message>
</log4j:Event>
16:59:06 monitor expected <

thanks for help