I tried to install a thrid-party OpenWrt image to a computer. After writing the image file to SSD and start booting, the kernel message prints at a really slow pace, although some of the timestamp seems to be normal.
Here is the result of dmesg. The printing pace is mostly of 2 seconds for one line, but the timestamp only increased few milliseconds. As it's too long I posted it to Pastebin: https://paste.ubuntu.com/p/ZJKfXfGDSk/
Is that normal? It takes me about 5 minutes to complete the whole booting process. Once it boots, it works flawlessly. Also this phenomenon won't happen when using Legacy boot mode and the booting process takes about 6 seconds before you can press enter to access the console.