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The slow execution of the export process seems to be related to URL attribut export. Magento stores the rewrite rules for URL management and the results are store in table url_rewrite. Sometimes the rows in this table may be outdated and no more necessary. And since the auto clean-up process in Magento is not well implemented, this table may grow and grow without limits, making the export process slower and slower. This sould should help you to increase the speed of Export profile execution:
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