It's bad if your synth is aiming to be a virtual analog. The correct behavior of extreme resonance, at least in a Moog-type filter, is self-oscillation [0], but

It's bad if your synth is aiming to be a virtual analog. The correct behavior of extreme resonance, at least in a Moog-type filter, is self-oscillation [0], but actually achieving that through digital subtractive techniques remains CPU-intensive and a cutting-edge filter design challenge, because all the action is taking place at the top of the spectrum, where sampling rates start to matter. A generic "clean digital" filter sound that can do typical resonant sweeps would be acceptable for a web synth, and a purely additive emulation like that of IL Harmless would be good enough for almost everything. There's no such thing as a totally worthless sound, but some sounds are more immediately useful for musical purposes, and letting the filter break usually indicates a low attention to detail. Low-quality digital resonance tends to have a "dentist's drill" timbre to it, even when it's not broken. A last thought: I don't know how your envelopes are made right now, but they matter a great deal to the timbre. The curvature matters, as does the speed. You can use a generic filter with poor resonance performance, but the overall result will still sound pretty good with quality oscillators and well-tuned envelopes. [0] https://www.youtube.com/watch?v=dVgIf71uWB4 https://www.youtube.com/watch?v=dVgIf71uWB4