You may notice that CPU usage becomes high when Acronis True Image is running a backup job. CPU's temperature increases and so does the fan noise. Upon checking the list of running processes you discover that the process consuming most of the CPU resources is TrueImageHomeService.exe. After the backup finishes, the CPU usage returns back to normal.
If you had an earlier version of Acronis True Image before, you may recall that CPU usage was not that high during backups.
Higher usage of available CPU resources is part of adjustments, made in 2017 and newer version of the software, to achieve the maximum backup speed possible on a given machine.
Factors of high CPU usage by TrueImageHomeService.exe
The CPU usage during a backup with Acronis True Image directly depends on the lowest of the two values: the speed at which the backup source data is being read and the speed of your destination disk. When running a backup from a fast source, such as SSD, especially PCIe-connected, to another similar device, your hardware allows data transfer at a very high rate, which means that Acronis True Image has to process much more data per second than it would if the backup was processed over a slow USB or network connection. Faster data processing means that more work needs to be done per second, more CPU resources are consumed, thus the CPU usage is higher. On the other side, creating a backup over a slow USB2 cable or through a 100 Mbps network (12.5 MBps) means that less data has to be processed per second, the backup goes at a slow pace, less computing resources are required for that and the CPU usage is lower subsequently.
Enabled backup compression and encryption also cause higher CPU utlization, because they require additional operations to be performed by the backup engine, TrueImageHomeService.exe.
Comparison with earlier versions of Acronis True Image
Earlier versions of Acronis True Image did not take the advantage of the full potential of the CPU when running a backup from a fast source to an equally fast destination disk. For example, when your hardware was able to provide 150 MB/s read speed from the backup source and 100 MB/s write speed to the backup destination, theoretically the backup could run at a speed close to 100 MB/s (the lowest of the two values). But as the earlier version of Acronis True Image (2016 or older) was not capable of taking all the available CPU resources, the backup could be running at lower speeds, e.g. 50-60 MB/s., consuming e.g. 40% of CPU. With Acronis True Image 2017 and newer versions, the CPU usage would be 100% and the backup speed would be higher, closer to the potential 100 MB/s limit imposed by the hardware.
Example of when the CPU usage would be low
Let's see an example when Acronis True Image would not peg the CPU at 100%. Imagine we create a backup from an SSD to a NAS device through an Ethernet cable. Let's say the SSD delivers 70 MB/s read speed, network connection is 1 Gbps and the NAS has an HDD with a real write speed around 35 MB/s. In that case the data flow speed would be limited by the NAS's slow HDD and, having a powerful CPU unit, the CPU usage during backup would be rather low, e.g. 30%. Low CPU usage is that case is explained by the small amount of data that Acronis True Image has to process per second (35 MB/s). CPU usage would be low as well, when backup source or destination is a USB2-connected disk.
In other words, the higher backup speed you observe, the more CPU resources you can expect to be consumed during that backup.
"Operation priority" setting
Acronis True Image has a setting called "Operation priority" under Advanced backup settings. This option does not allow you to lower the CPU usage when it is high. The "Operation priority" setting is not absolute: low priority does not mean low CPU usage. It only sets the priority of TrueImageHomeService.exe process relatively to other processes running in Windows. When there are not enough CPU resources for two processes, the process with higher priority takes them.
This article is about consuming the CPU resources by the TrueImageHomeService.exe process only. If you notice that other Acronis processes consistently peg out the CPU at 90-100%, please contact Acronis Support with debug logs and a memory dump of the Acronis process in question, created with ProcDump utility (see https://kb.acronis.com/content/27931, section 6B).