Performance penalty OpenWrt

The Xiaomi Mi 4A Gigabit and similar direct from China models are in your price range. Initial OpenWrt installation is complicated but once that is done you have a good basic home router with speed performance much higher than a WR841.

iperf3 runs at least 500 Mb on a local GbE link, it increases to 800 with -A 2 for higher CPU affinity.

This looks like a nice solution. Looking at the OpenWRT install - it does appear to be a bit of a challenge...
I notice warnings about the possibility of bricking the router when installing a snapshot version. Which is the default one for the gigabit version. I'll try and order both the gigabit and 100M version.
Do I need a chip programmer? Any recommendations for such a device - there seem to be many around...
Finally, not quite sure what you mean by it increases to 800 with -A 2 for higher CPU affinity

A bit of feedback.
A while back I ordered both 100M and the gigabit version of the Xiaomi routers. Flashing the 100M version was a bit of a journey. The Gigabit version went quite smooth.
Both routers can measure the speed up to 100 Mbps without problems, the Gigabit at much higher rates. In a lab setting (two Dell PowerEdge R210 connected via a Xiaomi) measured about 940 Mbps on the original firmware. The OpenWrt firmware showed an average of 920 Mbps in upload direction, 560 Mbps in download direction. So there appears to be a bit of a performance drop, but not enough to hinder our measurements.

I ended up getting 10 more of the Gigabit variant that I am installing at key points of our network.
Good advice! Thanks again mk24!

I've just moved my EdgeRouter-X SFP to OpenWRT (previously on stock firmware).

So far, so good, and has enabled me to sort an IPv6 issue that I couldn't fix with the stock set-up.

Connection being upgraded from ADSL (17/1) to VDSL (60/15) shortly, so will report back with some performance numbers.