After a small number of bug reports, Dymo has admitted that there's a slow printing issue with all versions of Dymo Software running on MacOS High Sierra. If you are affected by this, you would likely experience name labels printing out quickly, followed by a 4-12 second delay before your security labels begin printing.
If you haven't upgraded yet we recommend you wait until Dymo releases an update addressing this issue.
Dymo is aware and working on a solution.
Unfortunately there's no easy workaround for this issue. It does not exist on any OS before High Sierra, nor on any Windows devices. Some brave customers have downgraded their OS and found that it fixes the issue, but downgrading is very difficult, and you may run into other OS issues.
We are told the next update of the Dymo Software should fix this issue.