Cache sysinfo data, and only query for the data we actually use

[nightkr]

Description

Fixes #19. There's still room for improvement, but on my desktop this takes us from ~50MiB on startup and ~95MiB steady state, to ~8MiB steady state.

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

# Author

# Reviewer
- [ ] Code contains useful comments
- [ ] (Integration-)Test cases added
- [ ] Documentation added or updated
- [ ] Changelog updated
- [ ] Cargo.toml only contains references to git tags (not specific commits or branches)

# Acceptance
- [ ] Feature Tracker has been updated
- [ ] Proper release label has been added

[razvan]

indeed, weird api but it works