[Uzaaft]

printRepeat (CSI b, repeat the previous character N times) calls print() once per repeat, so something like \x1b[2000b ran grapheme checks, width lookups, wrap handling, and the integrity assert 2000 times for what is usually the same character on the same row.

Terminal.print was 24% of samples on a REP-heavy micro benchmark.

This PR just aims to add a fast path by introducing a chunking mechanism. anything that needs care (insert mode, grapheme clustering, hyperlinks) still falls back to per-codepoint print() inside printSlice, so behavior should stay unchanged.

Some profiling data:

Generated with some plain stupid logic:

D = "benchdata"
parts, total = [], 0
while total < 40_000_000:
    line = "x" + "\x1b[80b" + "y" + "\x1b[35b" + "\r\n"
    parts.append(line); total += len(line)
open(f"{D}/rep.bin", "wb").write("".join(parts).encode())

macOS (hyperfine, 15 runs, warmup 3):

	mean
before	2.360 s
after	1.166 s

And now the really interesting and promising stuff

Linux, 24-core NixOS x86_64 (poop, 6s sampling):

	wall_time	instructions	branch_misses	peak_rss
before	1.51 s	50.9 G	9.41 M	6.82 MB
after	562 ms	9.07 G	114 K	6.74 MB