It's only as slow as you remember because the actual performance was so bad that you can't physiologically remember it.

Maintaining (if not actively improving/developing) a piece of useful software without performance degradation -- that's a win.

Keeping that up for decades? That's exceptional.

[0] "so few changes": I'm not commenting on the amount of work done on the project or claiming that there is no useful/visible features added or upgrades, but referring to Eclipse of today feeling like the same application as it always did, and that Eclipse hasn't had multiple alarmingly frequent "reboots", "overhauls", etc.

[?] keeping performance constant over the last decade or two is a win, relatively speaking, anyway