Board Thread:Questions and Answers/@comment-5986608-20130628164100/@comment-15296152-20130813180446

The reason for those glitches is because the 2D hardware isn't capable of rendering so many sprite pixels on the same scanlines at the same time. The hardware is not set with a buffer that graphics get drawn to. All graphics are drawn in real-time (well, except for the 3D hardware which uses a 48 scanline-sized buffer, but that is updates per scanline in real time as well).

The system runs at a certain refresh rate, meaning there is limited time it can draw pixels on each scanline in real time (a row of pixels that make up a line on the screen). When time runs out of time for a scanline, any rendering it still needed to do gets aborted as it prepares for the next scanline.

Each sprite takes up a certain number of cycles per scanline it lays out on. Any sprites that are set with scaling/rotating take up additional cycles (I think double), and therefore, additional time to process. The bottom of your video shows the glitching far less than the top because the top has far more sprites overlapping each other, meaning more sprites per scanline.

Hope that helps describe the problem.