update a Window XP software to Windows 10

It is for a science research software

The software was written in C# in Visual Studio a few years back, it was successfully run on XP. I can open it in Windows 10 in Visual studio, the software will run, with two issues, one is the timer, or delay in step, the actual delay time is 13 times longer, for example, 1 s set in the program actually would delay 13 seconds. The second issue is the program sends a serial command to an instrument to use certain rate, it may work the first time, if the rate stored in the instrument is higher than what is set, for example, If the rate in the instrument is 5 ml/min, and my procedure set to be 2 ml, it will work. The very last step is 0.05 ml/min, so the next sample when I reset the instrument, it will not change the rate and would use the last rate or manually change the rate. I have a software person checked the code, the code is correct, as it has been working properly before. Very likely it is the .net issue.
If you are able to resolve these issue, then there will be just a simple calculation to be added. I would also like to duplicate some windows to do multiple parameters.