In java code, xml is transformed into pdf
we use saxon to prepare XSL-FO (from XML + XSLT)
Then we use fop 2.3 (there is no way to update yet) to transform XSL-FO into pdf

Problem:
Sometimes the transformation takes a very long time.
We take a dump at the moment of freezing and see that in the logs you can find a blocking of the image cache
In the fop logs we see that it takes a long time to execute

[org.apache.fop.fo.properties.PropertyMaker ] PropertyMaker.findProperty: src, fo:external-graphic

We register images in the local style with FS

<fo:external-graphic height="40px" content-width="100px" src="url('/xml/logo.svg')"/>

Please tell me what could be the reason, and is it possible to manage the image cache in fop?
I only saw options for clearing

org.apache.fop.image.FopImageFactory.resetCache()

Maybe something else?
I will be glad to any ideas