i have this problem on 1.8 and it's annoying sometimes
this image (2014-11-20_21.36.17.png) is not related with the resource packs, but it's a problem too. the mobs don't be affected by lightning. i discovered this bug when randomly i decided to spawn a lot of mobs...
this bug affect the lava too. look at that black stuff
in the creative mode servers that don't have the nether enabled, some players can troll you with this :/
this problem was NOT solved >😞
but my computer with optifine + mc 1.7.10 get normaly 40-80fps with medium-high graphics betfore the problem. now i get even lower fps (15-25fps)
Here's a crash report that Kumasasa asked for me.
i apparently have a similar issue on 1.11.0.5 in the Bedrock edition where mobs often try to jump over fences and slabs to pathfind.
(sorry if i posted it in the wrog place, i don't know how to report Minecraft Bedrock issues.)