The Filter MultiCheck is not designed for scenarios, involving such a large number of items, as it would be impractical to expect from the user to scroll down through thousands of items in order to check the ones he wants to include in the filter.
For such scenarios I can recommend using the Kendo UI AutoComplete:
... or creating a custom widget that can combine the server filtering and/or virtualization functionalities of a Kendo UI AutoComplete
, and the technique for creating a checkbox filter menu, as demonstrated in the following how to article:
If you need further assistance with the custom implementation, you can check out the Telerik Professional Services that provide custom-tailored solutions, and widget customizations that best match the specifics of the given scenario:
Let me know if you are interested, and I will arrange for someone from the team to contact you.
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