Bug report

Describe the bug
The memory usage seems to be exceptionally high when resizing large input images to a small dimension. For example:
Resizing a PNG with a dimension of 30000x30000 to 1x1 with vipsthumbnail consumes about 18 GB max, but resizing the same input image to 15000x15000 requires just about 0.8 GB.

To Reproduce
Steps to reproduce the behavior:

1. Create the input image:

vips black --bands 4 black.png 30000 30000

2. Resize the image to 1x1:

vipsthumbnail --size 1x1 black.png -o out.png

3. The maximum memory usage is at about 18 GB:

gtime -f%M vipsthumbnail --size 1x1 black.png -o out.png

18228176

Environment

• OS: MacOS 14.6
• Vips: v8.15.3