¿Que versión de slic3r tenéis?
Porque eso lo he visto reducido precisamente desde la última:
Mira por el gap fill speed.
Del changelog de slic3r:
Release notes for 0.9.7 (2012-11-23)
New features:
new distinct settings for support material speed and gap fill speed (the latter one allows to avoid resonance issues when printing the very fast zigzag paths filling thin regions)
Improvements:
solid fills and bridges are now filled better
reduced the amount of zigzag fills to avoid some shaking
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