The very first item on Affinity Designer's feature list [1] is "Pan and zoom at 60fps". You don't generally accomplish this by accident. They apparently wrote

The very first item on Affinity Designer's feature list [1] is "Pan and zoom at 60fps". You don't generally accomplish this by accident. They apparently wrote the engine from scratch to use hardware acceleration, and be usable on an iPad with a very small amount of available RAM [2]. There's no reason blur, in particular, must necessarily be slow. Everybody (and their phone) has a GPU that's more than fast enough to do that in real-time. I wonder if the (cross-platform) interfaces that Inkscape are using on macOS aren't hardware accelerated. Or if it's using some syscall which is cheap on some platforms and expensive on others. I haven't done any testing but I agree that Inkscape feels much slower than Affinity Designer. [1]: https://affinity.serif.com/en-us/designer/full-feature-list/ https://affinity.serif.com/en-us/designer/full-feature-list/ [2]: https://forum.affinity.serif.com/index.php?/topic/18079-what-vector-rendering-engine-does-designer-use/ https://forum.affinity.serif.com/index.php?/topic/18079-what...