id summary reporter owner description type status milestone component version severity resolution keywords cc 599 _FileListToArray costs O(N^2) instead of O(NlogN) code65536 Gary "Memory re-allocation is an expensive operation and as such, should be avoided. For _FileListToArray to read a directory with N entries, it will need to perform N ReDim operations, and with each ReDim operation costing O(N) (assuming that ReDim is implemented efficiently), _FileListToArray will cost O(N^2^). A very common way to mitigate this is to double the array size with each re-allocation instead of just incrementing it. Under such a system, you will greatly reduce the number of ReDim operations, down to log2(N), bringing the final asymptotic cost of the function down to O(NlogN), which is optimal. I am attaching a patch that will fix this problem. With large directories with about 300 files, implementing this simple change reduced the time spent by over half (from ~10s for 100 runs down to ~4.8s for 100 runs in my benchmark). Proportionally, the performance win will be even larger for directories with more entries." Feature Request closed 3.2.13.10 Standard UDFs None Completed