150+ FPS drop when using F7 mode

[Alphastorm07]

Title:

150+ FPS drop when using F7 mode​

Launcher Version:

1.4.3​

Modpack:

Direwolf20 1.7.10​

Modpack Version:

1.3.1​

Log Link:

​

Details of the issue:

I usually run the pack with around 150 FPS, but whenever I use F7 to check where mobs can spawn while mining, I lose nearly all my frames, dropping to around 3 FPS! Now I'm not sure what the process is that checks the light levels, but I'm pretty sure it can't be taxing enough to eat up 150 FPS worth of processing power.

EDIT:

Spoiler: Screenshots...

Before:

After

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[Crhymez]

Have you tried to limit your FPS to your monitors refresh rate?
Most monitors are 60, limit it to 60 but not with V-sync.

Also FTB doesn't accept bugs while players are using optifine.

 

[lenscas]

Have you tried to limit your FPS to your monitors refresh rate?
Most monitors are 60, limit it to 60 but not with V-sync.

Also FTB doesn't accept bugs while players are using optifine.

I fail to see how limiting your fps is going to work.

and yes you should try to get the same results without optifine first.

 

[Alphastorm07]

I fail to see how limiting your fps is going to work.

and yes you should try to get the same results without optifine first.

If I limit my FPS my frames drop even lower than 60, which I don't want. But I'll give it a shot without Optifine!

EDIT: It seems to be a random occurrence that I can't replicate, so I can't really expect anyone to solve it. When it happens, it a restart appears to fix it, so I can live with it if I must .