Longer queue select / deselect responsiveness is poor

[isaachinman]

Describe the bug From Mick:

This is probably difficult/impossible to improve now, but with longer queues there is also a multi second lag with select / deselect.

To Reproduce Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior A clear and concise description of what you expected to happen.

Screenshots If applicable, add screenshots to help explain your problem.

Additional context Add any other context about the problem here.

[isaachinman]

@Tintels I need your help on this one. Can you please provide some information as to how we can reproduce the problem (including demo accounts), and possibly a video of the delay happening?

[Tintels]

Long queue account bo@bo.nl PW Bo Short queue account so@so.nl PW So

On the iPad, Nokia 6.1 and the Nexus 5X the account with long queue takes and average of 3 to 4 seconds and the short queue account is well under a second. Obviously it would be great if you can make it both be under 1 second.

[isaachinman]

So, this actually comes down to Mongoose/MongoDB write speed. It turns out that the entire queue data structure is being written for each selection/deselection action.

For the bo@bo.nl account, there were 47 images in the deselected array, amounting to ~29kb of data being written with each action.

[isaachinman]

I've spent about 2 hours working on query optimisation. I am going to push this to the beta API and do some real-world testing, but there's an overwhelming chance what we're discussing here is premature optimisation.

[isaachinman]

This should be now fixed, with a combination of native and API performance enhancements.

[isaachinman]

3a3af7a

[Tintels]

Great stuff!