High CPU usage when sending notifications (both atKey or forText)

[cconstab]

Describe the bug

When sending a lot of notifications on low powered hardware the CPU gets hammered and notifications get delayed.

Steps to reproduce

1. First I send a lot of notifictaions (several a second) on a small CPU
2. Then monitor the incoming notifications and the time they were sent
3. And then spot the delay in receiving.

Expected behavior

Not to hit the CPU too hard

Screenshots

RSA operations seem to be the culprit for every notification

Smartphones

• Device: Pi 3

Were you using an atApplication when the bug was found?

No response

Additional context

I would have expected an RSA operation perhaps once but not for every notification. CPU profiler lead me to this conclusion I will upload the screen shots.

[gkc]

I'm addressing this within the larger piece of work re encryption future-proofing.