Various minor performance improvements to the subscription page

[absidue]

Various minor performance improvements to the subscription page

Pull Request Type

• Performance improvements

Description

This pull request adds a few minor performance improvements to the subscriptions page. I've been using these in my own build for a few weeks now and haven't noticed any problems with them. The changes in this pull request can be grouped into 4 groups and are the same across all 4 subscription tabs.

1. Initialise isLoading with true instead of setting it to true in the mounted hook. This avoids Vue rendering an empty subscription tab, then a loading one and then again with the content, as it now only has to render the loading one and then the one with the content.
2. Switch from using Array#flatMap() with a passthrough function to just using Array#flat() directly.
3. As we fetch the channel cache entries from the cache in the cacheEntriesForAllActiveProfileChannels computed property, we can just use the entries from that, instead of loading them from the cache again in loadVideosFromCacheForAllActiveProfileChannels().
4. At the moment we create an empty array, then push all of the fetched data into that array in one big call to Array#push, I decided that it would make more sense to just use the array with the fetched data directly, instead of copying it into an empty array first.

Testing

Check that refreshing your subscriptions and loading them from the cache both still work correctly.

Desktop

• OS: Windows
• OS Version: 10
• FreeTube version: 9ca2c74