Speed is something we work on constantly, but not a quick project. While things will get better over time, if you identify a pattern on a specific page / repeating group, email us and we can see if there is a quick win there. Saying ‘speed is generally quite slow’ isn’t specific enough for us to look into it.
One thing to note is that you should avoid using ‘Filtered’ except if you absolutely have to, as it’s slower than using search constraints.