By rolling through the left side of the spider(s) in the west room at the beginning you can skip shooting down the vine to get around them.
You can also jump through the spider webs to allow returning to the door without needing to kill the spider.
This method is the most consistent method for handling the Stalfos, but it requires a shield.
As an additional small timesaver after the Stalfos dies but before the chest spawns, if you aim the camera 45 degrees left of where the Beetle chest will spawn, you'll skip a small camera panning cutscene after the chest spawns. You can also C-up before the chest spawns.
By standing at the right spot and aiming correctly, it is possible to hit the crystal with the slingshot to open the gate to the heart piece. This skips flying the Beetle to the crystal and saves about 10 seconds.
With precise slingshot aiming you can skip flying the beetle over to the crystal switch to raise the water after the third small key.
Instead of climbing the vine wall and having to recross the tight rope, jump back to the vine you previously used. If you are low enough on the vine and gain enough speed, you can reach the second vine and then jump over to the Boss Door.
In the first phase, you must move Ghirahim's hand to one side, then attack from the other once he locks his hand in place. You can hit him three times before he will begin to dodge again. One recommended method is:
Ghirahim's second phase is slightly random, as he has four possible attacks. In general, you want to wait for him to be vulnerable, then attack in a specific pattern. It is possible to finish Ghirahim's second phase in six cycles:
It is important to slash first before spin attacking, as Ghirahim takes more damage when stunned. If the stab in the first cycle doesn't land, or you use a different combo, it will take seven cycles to defeat Ghirahim.
These are the attacks that Ghirahim uses:
In this attack, Ghirahim will hold his sword in a guard position for a second or two, then attack. This is the easiest attack to deal with, as he is vulnerable immediately.
In this attack, Ghirahim will disappear, and then reappear either in front of or behind you, with his sword held in a guard position. He is vulnerable immediately after reappearing.
In this attack, Ghirahim will hold his sword behind him to either side (sometimes hopping backwards first to gain distance), and then charge you. He is vulnerable while charging, but you have to time the slash carefully. As a safer alternative, you can spin attack, but you'll lose the chance at a six-cycle fight. As an even safer alternative, you can shield bash this dash attack.
In this attack, Ghirahim will summon five red daggers in a line and fling them at you. This is the worst attack to get, as he is never vulnerable during it. The fastest way to deal with this is to swing your sword to hit all five darts, thus cancelling the attack.
You want to get as few dart attacks as possible, and cancel those you do get as quickly as possible. One good strategy is to not Z-target until he is vulnerable, and to try to herd him towards the center of the room. This will minimize dart attacks and avoid him teleporting away from you when he reaches the edge of the arena.
To defeat the Bokoblin Archers guarding the tightrope in front of the boss door, it is normally required to use the Beetle to drop a bomb on the archers. However, this can be skipped by using the upgraded Hero Mode Skyward Strike to hit the Bokoblin Archers from the other side of the rope. With a good angle, you can hit both archers in a single Skyward Strike. A good way to get the angle required is to stand in the right corner of the platform near the rope, and aim for the left edge of the boss door.
There is a quick method for killing all three Stalfos at once using bombs and Skyward Strikes. Follow these steps:
You can speed up the above a little by throwing the second bomb in between the first Skyward Strike and the first spin attack, but the timing becomes tighter. If one of the Stalfos survives the second round, just finish it off normally.
In the eastern water room, you can skip the Mogma text near the web by running up the wall next to the first blue mushroom on the right. After getting the key, enter the crawlspace while being angled to the left, so that you can jump out of the crawlspace directly into the water, skipping the mogma text again.
In the final room with the bokoblin archers it is best to run towards the gap that has a skulltula during the first visit and fly the beetle from there. This makes it easier to avoid the arrows of the archers when flying the beetle. This trick is used only in normal mode speedruns where the longer skyward strike cannot be used.