I was quite lucky that the level was unoptimized enough that I could use a slower ending strat, while still getting a new world record!

I now use a Grenade at the first wall which helps getting good height on the second wall afterwards, you need good timing but it's nothing strict though. Furthermore I no longer use the big wall route, instead I found it to be much faster and consistent to use the floating square platforms. This makes it possible to get a direct path to the other side. In this run I touched the checkpoint at 11.845 which is crazy good seeing as my best ever is a 11.712. The ending is also different since I go for the right side instead of the left one, which is probably a bit slower. I just feel like it's a bit easier since you are already facing that direction so I just stuck with it.

While this is a new world record it's not optimized until one can incorporate Ico's ending skip into the run again. The time can easily go down to at least a 16s, possibly high 15s run if all goes perfectly.