Very familiar with open-source development. Going to offend many by saying so, but here's the unavoidable truth about what makes a project good or bad:
- Bad: developers only work on what they personally need and/or are dismissive of others' issues. Those same developers tend not to help others get started because they only care about their own problems.
- Good: developers work on their own problems + others' problems. Developers care about the quality and completeness of the project and work towards "finishing" the project, not just making it "good enough".
On principle alone, the plot window should not take more than a few seconds to appear, period. This problem has been around for a long time now, reported by multiple people multiple times. I have used Octave off and on for years and basically I can't use it more because my main need is also MATLAB does it faster and more consistently, therefore it is possible.
I would consider paying a small amount to someone to first find the problem, and then I might be willing to go in with others on paying someone to fix the problem.