Hey everyone, I’ve been diving into optimizing my nRF52833-DK board’s flash usage lately, and I thought I’d share my journey and insights with you. 
I noticed that when I build my application with the ‘Optimize for debugging (-Og)’ option, I run out of flash space, even though the board has 512kB of Flash memory. The terminal shows that only 237,056B is available, which is puzzling. I wanted to understand why this discrepancy occurs and how to free up more space, especially for DFU configurations.
After some research and experimentation, I realized that many of the KConfig options enabled by CONFIG_NCS_SAMPLE_MCUMGR_BT_OTA_DFU weren’t necessary for my setup. Removing unused configurations helped reduce the flash usage, but I had to be careful—removing some configs caused issues during DFU testing with the nRF Device Manager. It was a delicate balance!
I also discovered that adding more powered Zigbee devices, like the ECOSMART Connected LED Light Bulb, acted as effective repeaters, improving the mesh network stability. This wasn’t directly related to flash optimization, but it was a valuable takeaway for anyone working with Zigbee networks.
If you’re facing similar challenges, here are a few tips:
- Review your KConfig settings and disable any unnecessary features.
- Consider using optimized build options when debugging isn’t critical.
- Strengthen your mesh network with additional repeaters to avoid connectivity issues.
I’m now exploring further ways to tweak my configuration for even better performance. If anyone has additional tips or experiences to share, I’d love to hear them! 
Happy optimizing! 