loading circles appear when running

[peterdudfield]

Describe the bug

When using the play button on the UI, the loading circle is present quite a lot.

Even if we go back to what was loaded before (i.e maybe cached) the loading circle still apears

To Reproduce

Steps to reproduce the behavior:

1. press play, let it run for a few
2. go back to now, and let it run
3. loading circles still appear

Expected behavior

• second time pressing play, would expect no loading circles

Additional context

• n/a

[braddf]

Fixed with #755