SpiceCRM is fully built on HTML5 Standards. When it comes to browsers supported we thus also need a modern and compliant browser. Most of our developers use Chrome, Firefox or Safari. If you need to stick to MS Standards you will need to use Edge.
Still the speed difference will be noticable. The reason is quite easy to explain. SpiceCRM is built using the latest web technology. The complete system is based on webcomponents. Simply stated webcomponents are little containers on a webpage that have their compete own logic from the business logic, to the html code to the styles. Overall from a development perspective this is good news since it allows to build easy reusable pieces that can be reassembled literally easily in the app. This is the basic technology that enables us to be that flexible when it comes to the user experience (UX) in SpiceCRM.
The caveat is that this is amongst the newest of the new technologies. The standards are currently being put forward to the W3C (the World Wide Web Consortium https://www.w3.org) that defines the standards of the content being shared in the web. Google’s Chrome has ~65% of the global share of browsers (https://netmarketshare.com/browser-market-share.aspx) and even more browsers utilize webkit and the chromium engine. Google is very adamant in their view and pushing standards. they are also early implementing new standards and build tools like Angular (https://www.angular.io) that power SpiceCRM. With the early implementation of upcoming web standards browsers like Chrome simply are faster when executing and running web apps that leverage the newest technologies.
So yes – if you want to use MS Edge or if you are forced to do – SpiceCRM will work but other technologies and browsers might be more suited for the latest tech based Systems.