Describe The Bug

At first, everything seemed normal upon entering the world, where my FPS was in the normal range of 30 FPS. However, as time goes on, the FPS seems to be gradually decreasing, until the game suddenly becomes unplayable as my FPS is now hovering in the range of 1 FPS. The problem seems to fix itself after closing the instance and reloading it, but upon opening the world, the FPS still gradually reduces after a while. 
Upon opening the F3 Debug menu with pie chart, I discover that the "tick" portion is slowly increasing over time, especially if I'm in a cave and bat noise is around.
After going through the mod disabling process, I find out that Sound Filters were related to the issue.

Reproduction Steps

1. Create new world
2. Load world
3. Open Debug Pie (Shift + F3)
4. Find a cave and create some reverb (place blocks, spawn multiple bats)
5. Idle in place for about 10 minutes while not pausing the game
6. Observe that tick slowly takes a large portion of the pie and FPS gradually drops

Screenshots

Before disabling Sound Filter

Spawning in the world for a few second

Waiting in a cave surrounded by bats for 10 minutes

After disabling Sound Filter

Spawning in the world for a few second

Waiting in a cave surrounded by bats for 10 minutes

Crash Report or Log

Before disabling Sound Filter - frequent warnings with very high value

After disabling Sound Filter - only occasional warnings with low value

Operating System

Windows 10

Java Version

AdoptOpenJDK OpenJ9

Modpack Version

v1.3

Additional Context

A similar issue appears on Sound Filters' issue page, but the author seems to be currently inactive:
https://www.curseforge.com/minecraft/mc-mods/sound-filters/issues/27

Yup, will remove Sound Filters in the next update since there doesn't seem to be a fix for this.