I'm going to assume that this is your first hack Shizufuzu. (Judging by post count and how long you have been here)
This hack needs a lot of work. Aeon described your level design perfectly. Its very inconsistent, it ranges from easy to hard. Its like you were trying to make a Kaizo and a regular Mario hack. A lot of times you had obstacles in areas where you normally land. You also like to spam enemies around as well. This causes slow down, annoyances and memory issues. Such as this one:
The P-Switch didn't appear at all. It took me 5 minutes of running back and forth through out the level trying to figure it out. I randomly jumped up to the one place I hadn't checked and it was there. This is an easy fix, all you need to do get rid of some of the enemies.
Your OW is very plain, square and boring. You need to make it more random and decorate it more with hills, valleys, rivers and lakes.
Verdict: This hack feels really rushed and unpolished. It feels like you wanted to create your first hack and impress everyone with ExGFX insertion and addmusic. But it doesn't work like that, you need to put time and care into each level. Try and make the difficulty really easy in the first couple worlds and then rank up the difficulty at a good pace as the game goes on. Don't insert ExGFX for the hell of it, insert it because you feel like it fits your hack. I really recommend scrapping your hack and trying again. There are plenty of level design forums on this site in the tutorial section. Try and read up on a few of them to get a better idea of what it takes to make a good hack. Also don't forget this golden tip from this site. (You can see other tips where it says "Tip" at the top of the site)
Originally posted by SMWC Tips
Tip: There's a fine line between difficult and unfair. Avoid the latter.
Also 700th post WOOO