#221 'Ultra' compression on Deflate(64) compressor bloats memory

[Anonymous]

When using large word sizes, the memory used for
compressing skyrocketed, up to 36(!)MB. Increased
memory usage with respect to word size only happens
when Deflate(64) compressor is used and compression
level set to Ultra, which is very odd. After doing
file comparisons, it turns out that if all other
compression settings are the same (eg: dictionary size,
compression method, word size), the files generated by
setting compression level to Normal are identical to
the files generated by setting compression level to
Ultra. Thererfore, the increase of memory usage based
on word size is unnecessary. In the case of 7-Zip,
setting compression level to 'Ultra' should use at most
3MB memory for Deflate(64) compressor.