Bushra,
chart creation should not have any noticeable effect on server performance, so there is something wrong with your setup.
What does the "top" in your question refer to?
The first thing is to see if the chart creation is causing the slowdown. Run the same report with out dbr.chart so you see if your report slow query is causing the slowdown.
myDBR supports all major browsers. Newer browsers perform better and are therefore recommended. There is no recommended server configuration as it depends on the amount of concurrent users, complexity of the reports and most importantly, the report query optimizations. myDBR itself is quite light on the resource usage.
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myDBR Team