I'm sure others will give more feedback.
from my point of view having data and logs on the same drive are not necessarily bad - all depends on the workload.
If nothing else I would do the following
-Change maxdop to 8
- ensure maxmemory is set
- ensure Instant File Initialization is enabled
-Ensure that cost threshold for parallelism is not set to the default value of 5 – something around 50 is normally better but final value should be tested
-Buy a set of SSD drives and move the tempdb to those
- ensure tempdb has at least 4 files, 8 probably better on that machine spec
-See which trace flags are enabled
-Myself I normally set the following ones instance wide
---1117 - tempdb
---1118 - tempdb
---1222 – lock information
---3226 – remove backup successful info message
---4199 – enable all fixes