Desktop JVM memory: what the number means before you tune anything

A desktop JVM app that "uses 1 GB" is telling you almost nothing. The number to act on is the ratio of Java heap to total footprint, and there is one experiment that decides which half of the problem you have.

Heap small (say ~150 MB) but footprint large   -> native memory dominates; allocator territory.
Heap large, close to its cap                   -> a Java-side problem; start from heap info
                                                  and a heap dump. Allocator tuning will not help.

Take the reading after a real session — half an hour of ordinary use — not at startup. The whole question is behaviour over time.

The decisive experiment

Ask the allocator to hand idle memory back to the OS and measure the footprint on both sides. One run, on one machine — the shape is the result, not the figures: