The first delay is a long cycle of checking every file mentioned in the VSS writers metadata. There are 8 million of FILESTREAM blobs on that server. This must be what causes this cycle to be so long for that volume.

Please download the bundle here: https://storage.veeam.com/Fix_125973_aebe4c1eb0.zip

To install, do the following on Veeam server and any Guest Interaction proxies that you have:
1. Locate C:\Program Files (x86)\Veeam\Backup Transport\GuestInteraction\VSS\VeeamGuestHelpers
2. Rename VeeamVssSupport2003_X86.dll to VeeamVssSupport2003_X86.dll_old
3. Rename VeeamVssSupport2008R2_X64.dll to VeeamVssSupport2008R2_X64.dll_old
4. Rename VeeamVssSupportXP_X86.dll to VeeamVssSupportXP_X86.dll_old
5. Extract new versions of these 3 DLL files from the archive.