Critically poor performance in spiral shapes (expand stroke and what not)

[Bound by Beans]

Today, I attempted to work with spirals in Designer and Publisher, and discovered that an extremely slow export in Publisher was caused by spirals using a custom stroke curve width. Expanding the stroke resolves the issue before output, but this process is also very time-consuming. On top of that, there's no indication in the interface that Affinity is sweating over the calculations – until the beach ball starts spinning for a bit. During export, you have no idea what's going on. Not even that an export is in progress.

The problem arises when working with spirals that have a variable stroke width – for example, from thick to thin. The issue worsens as the number of turns increases: five is slow, ten is too slow, and twenty becomes unbearably slow when for example expanding the stroke. While Designer or Publisher does not freeze, the interface becomes nearly unusable for some time. And this is on an M4 Pro Mac, so really... There must be one or more performance hotspots – plainly visible at high noon.

I only discovered the root cause of the slow export by chance, and I must say that any creative use of spirals with variable stroke widths is effectively off the table as things stand. These are such inefficient algorithms that this should be considered a bug, not a feature. And when PDF export practically grinds to a halt because of it, we have a real problem.

Only 20 turns with slight stroke variation – that really shouldn’t bring Affinity to its knees.

Latest hardware, macOS, and Affinity 2.5.7 – including the beta.

[loukash]

Definitely a bug.

I just compared v2.6.2 with v2.4.2 (me still using the latter until all these bugs are fixed):

• v2.4.2 with a spiral like in your example, with rounded ends: export takes less than a second, the resulting PDF/X-4 looks perfect
• v2.6.2 with the same spiral: export takes about 5 seconds, and as a "bonus" the thin end of the spiral has been expanded to sharp nodes (known and annoying bug, and the main reason I'm sticking with v2.4.2)

[NathanC]

Hi @Bound by Beans,

Can confirm i've replicated and logged this issue with the developers, thanks for your report.