I would look at the state if the network (slow as in slow to retrieve data from outside country? Slow as in slow in the same town? How is data between ISPs?
I suspect you ae not the only one in country with this problem - why not create a web site that is designed to help developers and ISPs like yourself - place known size blobs on external and internal sites and on different ISPs networks in the country then measure the download from anyone's clients using small piece JavaScript that posts back to your site. You don't have to do I all - just enough that it is obvious to ISPs it's a worthwhile map of the country. Also once ISPs are interested use tracert to get maps of the networks more detail. The aim is to create a site to discuss just this issue - network latency in your country - everyone will care about it and you should garner kudos.
Anyway. Apart from that keep sizes low - avoid the latest JavaScript frameworks - they are way way too large. Be cache friendly - Minify whatever JavaScript you do use and give it a hashed name to allow you to know what is or is not cached
Hope that helps - let us know which country as well