Spudosoft xlsx emitter occupies more heap space

sur_mast

I have requirement to export the Birt report into xlsx format. I see Birt is using spudosoft emitter for xlsx format.

For less records , the export seems to be fine. if there is more records involved, then export takes lot of time and heap space is filled up. But xls export seems to be fine with limited 65 k records. Do we have any solution to get the xlsx export faster without occupying much heap space? I am using Birt 4.4 version.