2016 RDS slower than 2008R2, understanding

hi all,

knowledge: last year we migrate some 2008R2 Server to 2016. All new Server has performance problems.

old server: 4CPU, 32GB, 150 and more User, slow wifi network = no performanceproblems, user works fine

new server: With 4CPUs and 20 Users we have 98% CPU workload.! We upgrade to 6CPU, 32-64GB 50User, because more use can't work on one server.  

Now we use 2 Server with more CPUs to solve the problem.

is 2016 a step backward :-)

we know the RDS best practise, but I think 2016 with default setting (and without 100 registry settings and file modifys etc.) should be better as 2008RS2 RDS.

Chris