Expand server performance

[Susan Devan]

I have a 2012R2 Server, it is currently on two GB NICs Teamed, one of the bespoke software is really old, more like a Btreive type flat DB and it is currently holding over 1 Million + records.
We have 30 workstations, and while we know the software is either badly written or it is generating a lot more traffics than a standard SQL, we need to find a way to ‘fix’ this.
The server is a Xeon 3.3GHz/16GB/4x1GB on Adaptec RAID10 (Avg read/Write is 250-350Mbps)
I added the second NIC to team few months ago after yet another software update that added even more weight to the already slow software, before anyone say change software, we simply can’t because this is a bespoke system with 20 years of data which the supplier said they can’t migrate to SQL yet, and may not be a few more years.
I can see the bottleneck coming from the traffics as during peak time (when users start to moan about snail pace speed), the CPU is at 15%, Memory at 20% and the server still responding to commands at normal speed, but the Sent traffics is around 30Mbps to 50Mbps but can peak to 140MBps for a short burst of time. The Recv traffics is normally around 15-30Mbp during peak and will die down around 2-5Mbps.
Before I added the second NIC to team, the system for most if not all users can be locked in a freeze state for a minute or two as it is waiting for resources to be freed on the server.
As the supplier don’t seem to give out much info as to how their database operate. I am working blind here looking for ways to improve the situation.
The first I am looking to do is to replace the server hardware by changing the RAID and NICs to :
Adaptec 6805 (512MB+BBU)
8 x Samsung 480GB V-Nand SSD on RAID6 (6 drive on RAID and 2 Hot spares )
The database is 1.1TB and each year grow by 100GB so should be plenty of usage space.
Install a Quad Port Gigabit NIC to further Load balance
I am sure this will help a lot with the traffics as the server will now have more speed shifting data out from the database and the 4xNICs can spread out the Sent loads.
Do you guys think this will work ?
I also plan to add another 48 Port GBit switch as a backup on top of the existing one, would I benefit in any way if I were to sent 2 of the NIC connection to one switch and another 2 Server NIC connections to the second switch ?
And the final question is would I benefit from changing the server NICs from4xGBit to a 10GBe dual port card to allow faster sent traffics ?
Thanks for any help on this, sadly we are stuck with this software until further notice so not much else I can do other than keep adding hardware resources.