I am a long time Infuse user and never had any problems with stuttering videos - even with 80GB 4K content.
However I have a tv show in 1080p x265 with HDR and I got stuttering while playing. My ATV is connected via 1Gbit just like my NAS so I think its not a bandwith problem.
I have also other files containg HDR or even Dolby Vision but no problems. @james how can I submit an example?