Import Contact Issue
You have several options, which I detail below - but I think the most important thing to do is check your CiviCRM log.  It's likely to tell you what your problem is.

Past that:

One option is to adjust your php.ini settings to change the max_execution_time to zero.  You can also do this in civicrm.settings.php if you prefer.

Another is to import your data on the command line using the API CSV import tool - but this requires breaking up your data into separate entities (e.g. Contact, Address, Email, etc.).  This is very efficient on large imports but not worth it unless you can script it (e.g. with Pentaho Data Integration).

I agree that it's very likely that either geocoding or USPS address validation is likely a culprit - but the easiest way to test that is to disable, do a test import and check the result.

If you're a programmer and don't like using Pentaho, you could also try writing an importer that uses the advimport extension.