Experiment if using a baked RLE helps speed up quad textures using set direction & move for the RLE. This means no jaggy lines regardless of resolution & squashing. I think its only better than UV pixel sampling if you have alot of large repeating textures in the current view, but the method may reduce the need for zbuffer for baked RLE textures. This is only perspective correct on x axis vertical trapezoid (walls). We would need to bake RLE for y axis to do horizontal trapezoids with correct perspective and adjust the quad filler. But It would create snapping effect, if you merged rle x or y methods for a rotated floor scenario. This work reasonable well for walls vs sampling pixel color by UV method but UV is more drawCount heavy and has jagged lines at lower resolutions. I don't know about X1 or X2 clipping may need to fall back to UV sampling in that scenario.
This project has 2 filler versions: [1] generic quadFiller (faster & stable in rotation) and [2] xPerspective (slower & rotation snapping) The default texture is 200x200 has 365 drawCount. While at size 16x16 it uses 57 drawCount. On my android phone, this can render 5 large X-perspective quads at res 2 in single frame and 6 quads without perspective in a single frame. Texturing should be used prudently in vanilla scratch. Please use vLines costumes or STTF as much better performance alternatives. You may need fall back to pen textures for niche near field scenarios for STTF. I think @b9e vLine method is most optimal for walls. I never made a textured filler and wanted to experiment with baked RLE.