fix ~10x performance regression by reverting a change

[LGriffioen]

change was introduced with zip64 support

Fixes #311

Changes proposed in this PR

• reverted b3ca1e6#diff-d829f12a7b0fa38c616a3397c9ea1464287b0d0097dee344876fff88b4b28e39L316

Tests performed

• performance of loading 10,000 files that are zipped is ~10x faster than development, and roughly where it was before the Zip64 changes
• I'm not familiar enough with Zip64 to be able to test what impacts this change has on that functionality

Further info for the reviewer

• Performance with large numbers of files is critical for us. This 10x improvement is taking a 20s operation down to under 2s

Open Issues