https://devzone.nordicsemi.com/f/nordic-q-a/94242/smp-ble-file-upload-vs-mcuboot-upload-speedHi, Setup : nRF SDK 1.9.0 and nRF52840, with an External flash MX25L series. Using SPI (not QSPI) I&#39;m noticing a huge difference between speed of file upload over SMP BLE vs. MCUBoot DFU, both of which that are writing to external flash (SPI) inen-USTelligent Community 13Fri, 25 Nov 2022 12:27:24 GMThttps://devzone.nordicsemi.com/thread/397634?ContentTypeID=1Fri, 25 Nov 2022 12:27:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ce93fb09-3e08-4361-a974-d01023acdc70Sigurd Hellesvik<p>Hi,</p> <p>Is this what you are looking for?</p> <p>&nbsp;<a href="https://devzone.nordicsemi.com/f/nordic-q-a/86191/mcuboot-slow-with-nrf52840-zephyr-usb-cdc_acm-protocol">MCUBOOT slow with nRF52840 / Zephyr / USB CDC_ACM protocol - Nordic Q&amp;A - Nordic DevZone - Nordic DevZone (nordicsemi.com)</a>&nbsp;</p> <p>Regards,<br />Sigurd Hellesvik</p><div style="clear:both;"></div>