Gitlab issue board loads very slow

We have received a couple of requests where customers mentioned that it is taking very long to load issues in issue board and sometimes it ends up in 500 Errors.

I have tested myself for a couple of them and it takes nearly 6+ seconds to load a single issue in an issue board.

For example an issue board this small

Screen_Shot_2018-11-20_at_7.13.03_PM

When it loads it takes a long time to load.

Screen_Shot_2018-11-20_at_7.12.49_PM

It also sometimes don't load and ends up in 500.

Screen_Shot_2018-11-20_at_7.23.29_PM

ZD:

https://gitlab.zendesk.com/agent/tickets/108596

https://gitlab.zendesk.com/agent/tickets/108486

I think this is somehow related to #34510 (closed) @smcgivern can you please check?