How to Diagnose Stutter and Lag Spikes After Installing the Pack

Separate FPS from stutter

Low FPS is a steady frame rate problem; stutter is intermittent hitches. The optimization mods (Sodium, Lithium, Starlight, FerriteCore) mostly raise average FPS and smooth CPU load, so if you still get periodic freezes, the cause is usually something the pack does not touch: world generation, entity counts, or garbage collection from memory pressure.

Narrow down the cause

1. Does it happen while moving into new terrain? That is chunk generation. Lower Render Distance and avoid fast travel through unexplored areas.

2. Does it happen near farms or many mobs? That is tick/entity load. Lower Simulation Distance and reduce the number of active entities.

3. Does it happen at regular intervals regardless of location? That points to memory and garbage collection. Lower Render Distance, close background apps, and make sure allocated memory is not set too low or too high.

4. Did it start after adding a resource pack, shader, or extra mod? Disable it and retest. The pack is vanilla-friendly, so add-ons are the usual culprit.

Confirm it is not the pack

Test in a fresh, empty world with default settings. If stutter disappears there, your main world's terrain, builds, or entity count is the cause. If it persists even in an empty world, check your launcher's memory allocation and Java settings, since those sit outside the modpack's control.