Lots of small files are always slower than the same number of MB/GB as large file/s, because of the much-increased stop/start loin-girding events required. (Imagine one of each per 1KB file x 1000000, versus one of each x 1 for a 1GB file - 2 million events compared to 2 events for the same number of bytes)
If you can replicate a Created date not being 'stamped', by all means submit a Support Zip with debug-out (and path\name of an example)
If you can replicate a Created date not being 'stamped', by all means submit a Support Zip with debug-out (and path\name of an example)