I have HDSDR installed on 5 computers - 1 tablet, 2 laptops, and 2 desktops. Here's what I have found with them as far as performance with HDSDR and SDRPlay.
Any CPU with a Passmark score of less than 1000 is likely to be limited at least in some way - bandwidth, response, mullti-tasking, etc.
The Passmark scores for various CPUs in an alphabetical list can be found here, and are useful as a rough estimate of computer performance:
http://www.cpubenchmark.net/cpu_list.php
1. The Vulcan VTA0703 Windows 10 7" tablet has only 1GB RAM and the Z3735G processor and is the least capable - no USB port, you have to run it off the battery and it has only 2 hrs battery life with the SDRPlay. But it does well (sometimes you have to reduce the bandwidth) even when also running an external Bluetooth speaker (without one the sound is quite tinny). Passmark score 936
2. My Asus X205TA Windows 10 11.6" laptop with 2GB RAM and the Z3735F CPU is my favorite for its small size, portability and long battery life. It has USB ports so you can plug it in and charge it (dedicated power port) and still run the SDRPlay. It will stutter some in FM at 8MHz bandwidth but cut the bandwidth back and it's fine. HDSDR uses around 20% or less of the CPU most of the time. Passmark score 903
3. My Sony VAIO 13.3" Windows 7 laptop with 12GB RAM and an i5-2430M CPU has no problems at all, with USB ports and lots of performance, HDSDR using about 10% of the CPU. Passmark score 3378
4. An HP 610-1050f All-In-One desktop with Windows 7, a 23" display, 16GB RAM and an i5-650 CPU runs everything smoothly with HDSDR using under 10% of the CPU. This computer has the best sound, no external speaker(s) needed. Passmark score 3161
5. Finally an Asus CM6730 Windows 7 desktop with a 23" display, 16GB RAM and an i7-3770 CPU is a powerhouse with HDSDR using only 1-2% of the CPU. Passmark score 9372