As preparation for a Looker demo to some internal stakeholders, I opened 10 different Chrome browser tabs to show different Looks and Dashboards.
Having opened the 10 tabs, the Looker web UI performance noticeable deteriorated.
Changing a filter selection, clicking the ‘Run’ and waiting for a table to refresh had some odd side affects.
What kind of visualisations did you have open? Any with a lot of data labels perhaps?