That might be blending two things. The blocksize default is 100 KB. There’s a request to make it 1 MB.
The dblock-size is for a file of blocks, and usually set via “Remote volume size”. That default is 50 MB.
Choosing sizes in Duplicati covers this, but the Options GUI only highlights volume size, not blocksize.
If you’re starting a new backup, it would be a good chance to scale blocksize up by, say, a factor of 20.
Preview of security and bugfix release Canary 105 was some attempts at helping scale via cache size, however it’s a manual setting of CUSTOMSQLITEOPTIONS_DUPLICATI and isn’t well-documented…
Regardless, the chance for a faster recreate seems gone, and we’re not sure how far yours had gone?