Aquamirae adds detailed world generation, structures and creatures, so a modded frozen-ocean expedition can be heavier than a simple vanilla biome. Tune the base game first, then isolate add-ons that increase rendering or simulation cost.
World-generation performance context
Aquamirae 6.2.0 specifically documented a redesign of Ice Maze generation intended to reduce the number of generated structures while making the maze more varied. That does not make every modpack lightweight, but it is useful context when comparing modern builds with older performance reports.
Lower the expensive settings first
Render distance and simulation distance are two high-impact settings to test. Reduce them temporarily and compare frame rate and stutter in the same area before making smaller visual changes.
Test without shaders
Shaders can make ice and water expensive to render. Disable shaders while diagnosing performance so you know whether the slowdown comes from the content mod, rendering stack or both.
Watch entity-heavy areas
Large numbers of mobs and complex structures can increase simulation and rendering cost. Compare performance in quiet terrain versus a busy Aquamirae area to understand where the bottleneck appears.
Keep versions and dependencies clean
Performance problems can sometimes be secondary symptoms of outdated loader builds, conflicting optimization mods or mismatched dependencies. Maintain a reproducible profile and change one variable at a time.