Placing a bomb immediately after warping and then tossing it downward will save time over walking to place the bomb (even when it's placed as far away as possible from the cracked wall). You'll need to walk up and left before tossing the bomb, but the positioning is not tight and you have a generous amount of time to do so.

Coming out of the bombable wall, simply hold diagonally down+right to enter the warp optimally.

Coming out of portal (E), Link will often be misaligned from the tile grid due to entering the portal from the left side. If Link's horizontal coordinate when entering the portal is less than 1A60 (i.e. if Link is not flush to the pot when entering the portal), Link will come out of the portal partially clipped into the left-hand rail. This has some (mostly) negative effects as described below.

Attempting to move diagonally down+left won't result in any movement at all.

Attempting to move downward will result in Link snapping upward to a vertical coordinate of 0F80, which will increase the distance required to move down to the corner portal.

Holding down+right or right until Link is out of the rail will prevent this, which can save a few frames, depending on Link's initial position. If you hold right for too long you'll end up losing time, but the time window for this is not unreasonable -- you'll usually want to hold down+right for at least 2 frames to clear the rail, and can still gain time as long as you don't hold it for more than 5 frames.

Pressing up for a frame as Link exits the portal will instead snap him downward to a vertical coordinate of 0F88, which can actually be optimal, but this is generally not viable in realtime.