Occasionally I want to be able to use very long page sizes for special reasons. Google does fully index and cache the large page and all its contents, and all its keywords (or phrases) can be found in G's search results. But I have noticed that G is unable to highlight keywords beyond a certain point in long texts.
When I search G for such a unique keyword or phrase situated towards the end of my page the KWs are bolded in the SERP, just as they should be. But when I click on the link to the page G has cached G tells me in the heading "These terms only appear in links pointing to this page:", which is not true, they are only on the page.
It does not matter if I search for the phrase with or without quotes. If I do a single search (without quotes) for one unique KW together with several frequently occuring ones I can easily see at what point G cuts off highlighting the KWs on my page. Other SEs not tested.
The amount of text G is capable of highlighting appears to be constant. An example page: simple and pure HTML only, static, without any graphics, text only. File size is 65 KB. Of 1247 lines (according to MS Word) of the complete HTML source code G only highlights KWs in the 970 first lines. Of 7960 words (including code), the 6161 first ones. Of 50,930 characters, the 39,900 first ones, and of 64,200 characters incl. spaces, the 50,150 first ones. The page does not have a strong PageRank.
These are very old pages and not worth splitting or updating anymore. Still, there is a continuous although limited demand for the pages' information. I cannot know how many searchers actually use G's cached copy of the page, but for them the lack of highlighting makes finding the KW in the page more difficult, of course. Is it known where G's limit goes and is there something I could easily do?