We have an existing asp.net website with 56 dependence DLLs, it's take 6 minutes to finish a fully build, cause we want sitefinity CMS site and our existing website share same domain name, so we merge our website with a Sitefinity CMS site (extra 208 DLLs added in bin folder) together, after merge, it take nearly 1 hours to finish a fully build, it's extremely slow, nearly 10 times slower then before. We expect it will be slow that before, but not that much.
Any idea and/or advice are appreciate,
The number of dlls referenced by Sitefinity are just that references. They are not compiled as part of your build. They are just file copied so that won't be your issue.
You need to look at your build steps and what ones are taking the time. For me, I run my builds in the cloud on VSTS and the longest process is restoring the Sitefinity nugget packages as these have to be downloaded from the Sitefinity nugget service and this can take 3 or 4 minutes.
I agree with Jonathan and you need (start) to look more at your build system\process first.