[Bug]: Review verdict submission is fairly slow for certain add-ons

[abhn]

What happened?

When submitting reviews for certain add-ons, AMO takes 10 seconds or more of processing time before the action is in our system. This is undesirable as it slows down the review process.

Example AMO ID from @wagnerand: 2809791

What did you expect to happen?

The review verdict submission should go through with minimal processing time (2 seconds or less is desirable)

Is there an existing issue for this?

• I have searched the existing issues

┆Issue is synchronized with this Jira Task

[diox]

By nature, there is a lot of variance because of what needs to happen depending on the action, the add-on, the versions etc. It would be interesting to see if this only affects approvals or other types of actions.

This graph shows the POST requests to the review page have gotten slower and with more variations than before since ~July

Coincidentally, the requests to autograph does seem to have started taking more time since ~July as well (more data since it's also auto-approvals, so slightly less noisy graph):

[KevinMind]

Once we determine the plan, we should update this task with said plan.