VDI Profile Settings for Resilio Prior to 3.2

Custom parameter recheck_locked_files_interval, value is in seconds. The frequency at which the Agent will check to see if the file is still locked (in cases when it's not notified by the system). The default value is 600. Put there 60 (=1 minute) if it fits your use case. It's not advised to put too frequent of an interval, as the Agent will be consistently busy rechecking the file. Don't put a too rare interval either as some delays in synchronization will be observed.

Custom parameter torrent_rolling_checksum, can be true or false Put it as false. The Agent won't use the rolling checksum algorithm in order to find changed blocks. The Agent will still transfer only changed pieces, but only if these didn't shift! Since blocks of VDI files are pretty large, the chances of block shifts are minimal.

Disable differential sync, which can be Yes or No.
Set it as Yes for slow storage disks. In this case, the Agent will prefer to re-transfer the file instead of calculating the changed pieces.
Set it as No for fast disks so that the Agent rechecks the file and transfers only changed pieces. This saves the network.

Custom parameter download_priority, can be 0, 1 or 2
The default value is 0. Value 1 means "newer first", value 2 means "older first", zero means 'no specific order".

For this parameter to work, file system notifications must be working. Note, that cloud storage and some Linux-based systems and storages don't support file system notifications.
This is the sorting of files in the active upload\download queue for the receiving Agent. Please note, it's not a prioritization of files across the whole set of data! This parameter only applies to the active queue of files. For example, it's known that AgentA needs to transfer 5 files to AgentB, file1 is the latest. We may assume that AgentA is still rechecking file1, so we may put value 2 for Agent B to start receiving the oldest file first which is most likely is already checked by the source Agent.

Additionally to those, manually do the following adjustments (not included in the VDI preset).

Reduce file size for versioning in Archive

By default files of size smaller than 1000 Mb keep previous versions in the Archive. the size threshold is controlled by the Profile parameter Max archive file size. If files change frequently, a lot of file versions will be kept in the Archive, which will take a lot of storage space.
Reduce the value to 100 (MB). With this, file versions of bigger files won't be stored in the Archive.

Edit local FileDelayConfig to add VDI extensions

On every Agent that may introduce changes to the large files, edit its FileDelayConfig file located in the storage folder. Add primary VDI extensions there or edit their values if they are already present: set a 300-second delay for processing these files (for example, "*.vhdx":300). Be sure to preserve json format of the file. This helps the Agent to access frequently modified files less often.

Case sensitive

Keep in mind that FileDelayConfig is case sensitive. Therefore, if you get some vhdx files with capitalized extension, add one more filter: "*.VHDX":300

With these, it's expected that the Agents will perform minimum disk operations and won't be stuck on continuous attempts to synchronize the files which apparently cannot be synchronized at the given moment.
Seen metric is 3-3,3 minutes to deliver 2Gb of changes in a 10Gb file, from the moment user logged out (=user's Profile changed) to the moment the Profile is fully available on 16 other computers.