CF10 and CF9 run on Java plus CF10 also has tomcat instead of Jrun. If one of the Java virtual machine parameters is reaching a limit you can get poor performance and stability.
With tomcat connecting to IIS you can do well to check the date and byte size of your ISAPI_redirect.DLL since there was an update to that in CF10 update 5 onwards and another in CF10 update 11.
You mention logs are ok. I take from that the details in CF10\config\wsconfig\N\"ISAPI log" are what you expect to see?
If you have CF developer or enterprise CF Monitor can help resolve something slow.
If you are familiar with Java then you can use JVM logging and or JDK JMX tools jconsole and jvisualvm to see how the Java is going with its heaps and garbage collections. JMX can also be useful to see how the tomcat connector is performing at the CF end.
CFSTAT can be useful on CF9 tho I find it less so on CF10 tho since it is available try use that as well case it helps.