Also providing the link of the documentation - “About using DirectQuery in Power BI”.
And lastly also providing a link where a query was asked onto the forum about the “Performance comparison between DirectQuery & DataImport” and some really great points were discussed in this post. Also the links of the queries posted onto the Power BI Community Forum.
Hoping you find this useful.
Thanks and Warm Regards,
Harsh
Refer other implications section under the given link of the documenatation -
Refer this blogpost where steps are provided to convert. Might be useful in your case.