We do sometimes get reports of One Step Checkout loading slowly, but there is nothing we can do in terms of our package to make loading faster.
OneStepCheckout is a wrapper around your default checkout/onepage, therefore the checkout takes the same amount of time than all 6 steps together in checkout/onepage.
The speed issue needs to be solved for Magento in general and the issue is a bottleneck in system resources. Either there is an issue with bandwidth, database query speed, disk space or memory or similar.
Please have your hosting provider work on the performance issue. The issue can be as simple as invalidated Magento layout cache or you may have issues with what I listed above, it is the system administrator who is able to solve this, the issue is not caused by malfunction of One Step Checkout package.