Slow performance when using classic ASP with ADODB on Window 2012 and IIS, Oracle Database

I have an ASP classic web application running on IIS 6.0 and Windows 2003, it uses Oracle Instant Client 10g and ODBC to fetch data using ADODB.

I have moved this application to IIS 8.0 and Windows 2012 using Oracle Instant Client 12c and ODBC to fetch data with ADODB.

The application works as expected, but web pages accessing the database take longer than in the previous environment. I have run queries in sqlplus with 10ms execution time, running the same query with ASP, the execution time is over 100ms. I think this is what is causing my moved application to take a long time.

Question:

• How can I track / debug this issue?
• Is there something about switching from W2003 / IIS6 / Oracle Instant Client 10g to W2012 / IIS8 / Oracle Instant Client 12c that might affect performance?
• Any other tips?