Indeed. Filter effects in Inkscape are its Achilles' heel, and although the performance (apparently) improves with each new version it's something that seems to be a continuing problem compared to commercial packages. General workarounds include using layers and hiding filters that you don't need displayed all the time, reduce geometry and nodes, and simply make sure enough RAM is available for the program.
I do know for a fact there have been several GSoC projects addressing this very issue. It's a pity that it's so much work in improving its performance, but if it was easy it'd been done ages ago. This is why commercial software sometimes wins out - paying people to work on the boring, tedious but necessary stuff results in fixing this issue, but this isn't an option for most open source so you take what you can get.