Move Windows server 2012 R2 to Windows Server 2019 IIS w3wp.exe 100% CPU usage

Move the web application from MS Windows Server 2012 R2 to MS Windows Server 2019.
The same , IIS .net SQL, but new server just starting to have a high Request 100% CPU, every Core is of w3wp.exe Apppool, although the new machine specification is almost double Try to use from User. Really use Online Load Test and JMeter. Same result. Old server normally 10-30% CPU. New server 100% CPU Hold and still.

Old Server  [Stable used 7 years]
DELL® PowerEdge® R420 Server , Intel® Xeon® E5-2420 Processor 1.90GHz X 2 (12 Core 24 Thread)
8G ECC 1333MHz X 2 (16G), 300GB 15K RPM 6Gbps SAS 3.5" X 2 [Raid 1]
MS Windows Server 2012 R2 Standard (64Bit) IIS8 ASP.net 4.0 , 32-Bit Disable ,SQL 2012 Express

New Server 
DELL®PowerEdge® R640 Server , Intel® Xeon® Gold 5120 Processor 2.2GHz X 2 (28 Core 56 Thread)
32G RDIMM 2666MT/s X 2 (64G), 960GB SSD SAS 12Gbps SAS 2.5" X 2 [Raid 1]
MS Windows Server 2019 Standard (64Bit) IIS10 ASP.net 4.0 , 32-Bit Disable ,SQL 2017 Express

Old Server and New Server

- FTP files from the old server to the new server The same directory placement structure, set the same permisson, solve only the IP as a new device.

- IIS set up Apppool like an old server Only some of the settings for IIS8 and IIS10 are the same.

- SQL database copy and then reattach (.mdf, .ldf) check rebuild index.

- Change connection string Connect SQL on the old server w3wp.exe CPU 100% is the same.

- The new server was first launched. There were 2,713 Threads at the time. About 1,600 old machines Threads

- The web application uses stackify Retrace to capture Error/Log and fix Error.

Server Location same rack ,same network workgroup

I need your help as soon as possible.
Thank you , Sorry about my English.

Start [New Server]

Load test (JMeter) [New Server]

Load test (JMeter)+ Real Production [Old Server]Advanced Setting [Application Pools] Old and New server