There are quite a few things to tweak that can lead to much smoother transfers, so I'll make an unordered list to help.
mount -o nocto,nolock,async,nconnect=4,rsize=1048576,wsize=1048576 rsize and wsize are very important for max bandwidth, worth checking with mount after linked up nocto helps a bit, the man page has more info nconnect helps reach higher throughput by using more threads on the pipe async might actually be your main issue, nfs does a lot of sync writes, so that would explain the gaps in your chart, needs written to physical media before replying that it's been committed so more data can be sent. sysctl.conf mods net.ipv4.tcp_mtu_probing = 2 net.ipv4.tcp_base_mss = 1024 if you use jumbo frames, that'll allow it to find the higher packet sizes. fs.nfs.nfs_congestion_kb = 524288 that controls how much data can be inflight waiting for responses, if it's too small that'll also lead to the gaps you see. subjective part incoming lol net.core.rmem_default = 1048576 net.core.rmem_max = 16777216 net.core.wmem_default = 1048576 net.core.wmem_max = 16777216 net.ipv4.tcp_mem = 4096 131072 262144 net.ipv4.tcp_rmem = 4096 1048576 16777216 net.ipv4.tcp_wmem = 4096 1048576 16777216 net.core.netdev_max_backlog = 10000 net.ipv4.tcp_fin_timeout = 15 net.ipv4.tcp_limit_output_bytes = 262144 net.ipv4.tcp_max_tw_buckets = 262144 you can find your own numbers based on ram size. Basically those control how much data can be buffered PER socket, big buffers improve bandwidth usage to a point, after that point they can lead to latency being added, if most of your communication is with that NAS, you basically ping the NAS to get the average latency then divide your wire speed by it to see how much data it would take to max it out. Also being per socket means you can have lower numbers than I use for sure, I do a lot of single file copies, so my workload isn't the normal usage.
