`direct-phi` XSL transformation exceeds 100ms threshold on large XMIR files

[volodya-lombrozo]

I'm getting performance warnings when running lints against eo-runtime:

[WARNING] XSL transformation 'direct-phi' took 119ms, whereas threshold is 100ms

What happens: The selector //o[contains(@base, '.φ')] is a linear scan over all <o> elements. On large XMIR files generated from bytecode (thousands of objects) the sheer volume of elements pushes the otherwise O(n) transformation over the 100ms threshold.

What should happen: The transformation completes within the 100ms threshold for typical XMIR files.