Donsullivan wrote: I have a 2017 MBP 13' i7,16GB RAM. 1TB internal SSD and one of the Samsung T3 drives.
The drive contains a small piece of software called 'T3 Security Enabler' for Windows, Mac and Android. Basically it allows you to encrypt the drive with a password, which you will need to type in.
I just ran a AJA system test performance test of the Internal SSD vs External T3 that might help as a baseline. Internal 1TB SSD External 1TB Samsung T3 Samsung list the transfer speed of the T3 drive at Up to 450MB/sec and you can see above that it actually delivers close to that speed when connected to a 2017 MBP 13'. Samsung suggests the transfer rate of the T5 is Up to 540MB/sec. It seems you're looking at 25% theoretical performance improvement with the T5 vs T3 but it's not clear whether the MBP can actually deliver that additional 25% performance increase.
In my experience, the Internal SSD is 3x faster than the T3. If the T5 runs at the same relative speed vs specs, then the internal would only be 2.5x faster than the external.
The bottom line is that the external drive will always be significantly slower than the internal drive. However the speed of these new drives is such that you will likely not notice the different between the 2 except with the most demandingly complex 4K video editing. Both the T3 and T5 are limited by the SATA III connection (550MB/sec) these drives run through. An internal SSD in a Mac is PCIe. USB adds overhead of about -20% to these externals, so max real-world speeds over USB 3.0 is around 430MB/sec and 800MB/sec for USB 3.1. The new T5 (USB 3.1) is bumping up against the maximum speeds possible over SATA III. The only way to ever make externals faster than 540MB/sec, would be to switch to a PCIe or RAID variant.
PCIe requires more power than is available through USB and heat is an issue. RAID is, of course, is not reliable enough.
Samsung claims 'up to 450 MB/s' for the T3, and 'up to 540 MB/s' for the T5. Let's say that you were copying a 3 GB video file from one of these SSDs to the internal SSD, and that there were no bottlenecks other than the speed of the external SSD. This might not actually be the the case, but let's assume this for the sake of simplification. 3 GB / 450 MB/s = 6.7 seconds to copy the file from the T3 to the rMBP, if you are lucky enough to get sustained maximum speed 3 GB / 540 MB/s = 5.6 seconds to copy the file from the T5 to the rMBP, if you are lucky enough to get sustained maximum speed These calculations don't substitute for actual benchmarks, but may give you a rough idea of what to expect.