slow I2C in OLED updates using U8x8

Apologies for cross posting, but I now realise I started maybe in the wrong subforum.

I'm looking for ideas what to investigate next to iron out a problem with slow I2C in OLED updates using the U8x8 subset of u8g2 lib. I am using hardware I2C on A4/A5. My project is functioning correctly on an 8mhz pro-mini, but the OLED updates are super slow. On my scope I can see SCL running at about 5KHz.

Main topic is here: https://forum.arduino.cc/index.php?topic=632733.0

I suspect your MCU could not handle the job. That library is pretty "heavy", especially if you use a lot of graphical elements.
With setup like yours you should get only few FPS.

I should have updated here as in the "main" thread -- I have this solved and the problem was that I had mistakenly used the software I2C constructor to create the u8x8 object. Changing this to the hardware constructor got me where I needed to be. It now updates fine at 400KHz.

I am using the u8x8 subset of the library which does not do much graphics, does not use a software frame buffer and only provides access to the OLED via native 8x8 pixel "tiles". It is a very lightweight subset for situations with limited requirements. I think the run-time impact is comparable to SSD1306Ascii, although it takes forever to build in Arduino IDE.

gardner:
Apologies for cross posting, but I now realise I started maybe in the wrong subforum.

Apologizing for cross posting doesn't make it any less against the rules. In the future, when you need your topic moved to a different subforum, please just click the "Report to moderator" link and request it to be moved there.