Videos play ok on iPhone but not iPad?

I have iPhone 6 with 10.1.1 iOS and latest iXpand app, I try play a small 200mb MKV hevc x265 file and on the iPhone it plays fine.
But on the iPad it stutters video and the video will stop completely while audio is still going or the video is very very laggy, obviously unwatchable.
It’s like this for a few movie files, some are ok on the iPad but on iPhone everything is fine.

The iPad is few years old I cleared some space ot of the 16gb so there’s about 9gb left, I’ve tried transferring to vlc with the open in method and even in infuse media player and it still doesn’t work.

Could it be the iPad has gotten too old and slowed down?
Just doesn’t make sense.

If you have similar issues with infuse and vlc the ipad itself could be the problem. 

What is the iPad model and iOS version?

Can you upload a sample file to dropbox and PM a link so I can test and see if I can recreate the issue? 

Check the setting of video. Sometime it vary the resolution 

I don’t know which iPad model you are using?
I am using iPad pro without any problems. This is most likely due to the lack of memory or the network settings of the old iPad models. You can clean up the cache or useless files.

Which iPad model are you using?