performance - How to ask antivirus software to work slower and hence use less disk access?

It is our policy for our end-user's computers (usually laptops) to have high power CPUs, GPUs, RAMs (no less than 16GB) and HDD space (1TB), but we save money by choosing lower rotation speed of HDD. We have very high rotation speed for our servers instead. Usually it works quite good, but antivirus software is raising problems. I can observe in Task Manager that if total (from all the processes) disk access is more than 4-5 MB/s, then the Taks Manager indicates 100% use of disk access and the other applications are slowing down visibly. Usually the antivirus software, especially scanner process is consuming the highest part of the disc access. Of course, I can assigner lower priority for antivirus software but this has impact of CPU use (which is not problem). But is it possible to slow down the disk access of antivirus scanner process? It is OK, that each downloaded file, each accessed web page is scanned in real time, but I don't see the necessity to have high disk access and express resource consumption for the long-running background disk scanner processes. We use many of our computers for programming, that is why each of them can contain around 5.000.000 files or more (no more than 15.000.000 files). So - scanner is trying to process quickly all those files and the work is impossible.

And regarding the option to do scans during idle/maintenance time. Well - it is important to stress that we use mainly laptops for the end users, many of them take their computers home, have flexible schedules. So - there is no time window that could be planned especially for the maintenance activities. So - this is no option. I wonder why antivirus companies are not thinking in terms of customer satisfaction?