I tried exFAT in order to use my external hdd on both mac and windows but I found it's so much slower than HFS+. The speed is noticeably different when I tried to fast forward movies (over 4gb).

exFAT was recommended in this question.

  • There also is a heavy i/o speed decreate when accessing exFAT formatted volumes through Java applications. We have got experience with CrashPlan that moves exFAT located archives roughly 5 times slower compared to archives stored on HFS volumes.
    – Pro Backup
    Jul 24, 2012 at 13:29
  • Did you format your disk with Windows or with Mac OS? Dec 11, 2012 at 9:19

1 Answer 1


exFAT is a file system optimized for flash drives, meaning storage devices without moving parts where seek times are constant. It sounds like you're using it for a mechanical hard drive – which is what's causing the poor performance that you're experiencing.

You should reformat the drive to HFS+ or FAT32 and only use exFAT for solid-state drives.

ref: http://en.wikipedia.org/wiki/ExFAT

  • Why only SSD? Does that include SSD drives or just flash drives?
    – William
    Jan 29, 2017 at 22:47
  • @William SSDs (solid state drives) are flash drives (a.k.a they're built with memory -flash- cards instead of a rotatory disk with a mechanical head). With HDDs, you have to wait until the head is on a specific sector to start reading data, but flash drives (SSDs or whatever) read almost instantly. exFAT is designed to use that second type of hardware. Mar 16, 2017 at 4:45
  • @AlejandroIván hmm I'm sure flash drives don't have the same read and write life span of SSD but that might be true. So if exFat is the new Fat32 why is it only intended to work with SSD then?
    – William
    Mar 16, 2017 at 15:33
  • 1
    @William ah, that. For some reason, Windows formatted exFAT usually have problems on other systems. The best way to make it work is to re-create the partition from macOS. At least that happened to me like 2-or-so years ago. EDIT: Of course, backup your data before doing anything else (I know it seems obvious, but sometimes even experts underestimate this and then lose all data... it happened to me once too). Mar 16, 2017 at 15:46
  • 1
    I don't believe this answer is correct. It is correct that exFAT is "optimized for flash drives" (according to Microsoft) - although those optimizations actually are quite minor. However, the conclusion in this answer that when the system is optimized for flash drives it must mean worse performance on non-flash drives - that is not correct. The optimizations in exFAT for flash drives do not diminish performance on non-flash drives.
    – jksoegaard
    Jan 6, 2022 at 10:32

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