Optimize APP startup time by lazily import some packages

As pointed out by @ahmil, some packages are unnecessarily eagerly imported leading to slow startup time (see below profile log), we might want to lazily import some of them.

import.log

added app label

assigned to @g-haoyuyang

created branch 2295-optimize-app-startup-time-by-lazily-import-some-packages to address this issue

created branch 2295-optimize-app-startup-time-by-lazily-import-some-packages-2 to address this issue

mentioned in merge request !2401 (closed)

mentioned in merge request !2402 (merged)

@g-haoyuyang: Here is an issue related to this: #2214

Not sure if you want to look into this within this MR or do it separately, up to you.

Thanks I would have a look!

mentioned in commit 5f02437e

closed with merge request !2402 (merged)