Well, two observations:
a) Download: 12.96 Mbps Upload: 71.81 Mbps = 84.77 Mbps total >> 10 Mbps
b) cpu0: 70 +/- 8 cpu1: 91 +/- 0: this leaves at best 100-70+100-91 = 39 % CPU cycles available (with 100% equalling one CPU)
See https://forum.openwrt.org/t/r7800-performance/15780/4 for some discussion of potential r7800 issues.