We are sorry to hear that you have such issue.
1. We need the document where rendering distortions were observed. Also it is not clear what you mean under “vertical search” and how this function should work.
2. This was handled via Live Chat.
3. Please report us these exceptions, we will investigate them. There is also a set of tips which can increase performance. First of all, try to use HTML-rendering mode (GroupDocs.Viewer 2.0 – Enhancements and New Features in the Document Viewer for .NET Library (Part A) , section “HTML-Based Rendering Mode”). Second tip is to use “PreloadPagesCount(1)” method. When using this method GroupDocs.Viewer will begin to load document to the client-side when first page of the document will be converted. When this method is not used, GroupDocs.Viewer converts all pages of a document and only then sends it to the client-side. Also, if this is possible for your business-logic, you can disable thumbnails (“ShowThumbnails(false)”) - this will increase performance too.
If you will have more questions please feel free to contact us.