Feed rendering performance

Sometimes it takes around 500-1000ms to open the feed that has already been loaded before (in prod env).

This is most likely related to the FeedItem component since replacing it with a dummy component makes the rendering much faster.

• Using fixed dimensions for media attachments should improve things a bit since it removes the potential style recalculations that need to happen on image load. (#95 (closed))

• parseFromString from linkify can be called lazily, only when the user clicks / hovers the link:

• delayed FeedItem rendering starting from the 3rd visit #85 (closed)