UI: reduce updating time for home screens

[spalmer25]

Context

After a few tests on the weekly test network, we discovered that the signing process was not fast enough.

A comparison of the signing speed was carried out, and commit Remove custom screensaver. Users can enable custom screensaver from Ledger settings clearly had an impact on the signing time:

Among other things, it adds an update to the home screens after each signature, which slows down signature time.

Suggestion

• no longer update all the data needed to display the home screens, but only those that are likely to have changed.
• stop updating the HWM screen at the time of signing
• update the HWM screen on both click

Results

[ajinkyaraj-23]

Better to add a description in Readme that to see latest HWM on nano devices , press both buttons.
Add a seperate heading called "how the app works " or something like that. Then add a single section about HWM for now. We can expand that later in another issue.

[ajinkyaraj-23]

Also, did you test the latest signing time after these updates?

[spalmer25]

Also, did you test the latest signing time after these updates?

Yes, you can see the result for ED25519 of the 3 last commit in the Results part of this PR:

Time elapsed for derivation type : ED25519_tz1dyX3B1CFYa2DfdFLyPtiJCfQRUgPVME6E is : 78.30447840690613

Time elapsed for derivation type : SECP256K1_tz2GB5YHqF4UzQ8GP5yUqdhY9oVWRXCY2hPU is : 58.6905243396759

Time elapsed for derivation type : SECP256R1_tz3UMNyvQeMj6mQSftW2aV2XaWd3afTAM1d5 is : 58.6864333152771

Time elapsed for derivation type : BIP32_ED25519_tz1VKyZ3RFDwTkrz5LKcTc6fcYqZj6pvsyA7 is : 144.5561113357544

[ajinkyaraj-23]

LGTM