A lot of work was done over last 3 weeks. Finally moved server part from shared hosting to my own VPS. And finally moved away from apache/php SSE (Server Sent Events - data channel from server to browser) and Ajax (data channel from browser to server) to more lightweight and fast Node.js and web sockets technology (double way server-browser text and binary communication over TCP). Now there is no need to base64 encode JPEG data that was previously streamed over SSE as SSE allows only text data to be sent. Now both JPEG binary and control/telemetry text data is transmitted over single web socket. That gives at least 30% less bandwidth requirement for server-browser link and considerably reduces control latency.