Which is faster FVH or Unified Highlighter?

[Shubham_Mittal]

Hi Team,

I have to perform highlighting on document "content" field which is basically of type "text" and is also stored as term vector with_positions_offsets in index for highlighting.

I perform basically normal text search , keyword search, boolean search , phrase , fuzzy and proximity, wildcard and search using aggregrations. 

Currently i am getting high cpu utilisation with unified highlighting on a fetch size of 100 on an index of 600 mb data with a concurrent requests of about 15000 on a 1 core and 2 GB ram system. Also i am retrieving two fragments and my fragment size is 70 characters.

Can you suggest if using fvh highlighter in my usecase would 
1. Fulfill my highlighting needs which currently unified highlighter is doing.
2. Improve the search response time and lower the cpu.

What are the best recommendations regarding the usage of highlighting. I have already read the documentation, so please suggest something from experience and usage of the two highlighters.