Ability of PlusMemo at handling large amounts of text

Introduction

PlusMemo is very powerful at handling large amounts of text. Most applications will run happily without concerns about how much text is contained in the component. But if text size can exceed a few MB, you must be aware of practical limits, to avoid undue load on the system.

The practical limit greatly depends on hardware configuration, software configuration, and tolerance of the user to system degradation. It can range from a few MB to a few hundred MB. We provide below recommandations that in our experiences are on the safe side. If followed, we are confident that you will not receive negative feedback from your users. If you need to reach higher levels of load, we recommend that you experimentally determine whether the resulting application behaves acceptably or not.

The effects of too much text

Theoretically, PlusMemo can handle more than one billion characters. However, past a certain value, you will experience one or more of the following annoying effects:

• Unresponsiveness to user typing and other editing operations, particularly at the beginning of the text;
• Operating system slowdown due to swapping and resource consumption;
• Unresponsiveness to keyboard navigation and mouse actions in the component.

Recommendations

Our basic recommendations concern both the number of characters and the number of paragraphs. The number of characters that can be handled easily depends mainly on the amount of RAM in the system, and should be kept below half of the RAM amount. The number of paragraphs is a complex function of RAM amount and processor power. We provide here recommendations for a few common configurations.

With syntax highlighting, maximum number of characters should be divided by four, the number of paragraphs by two. These recommendations are based on an average of one highlighting boundary every 25 characters, which is a quite heavily highlighted situation.

These data are summarized in the tables below:

Without syntax highlighting:

With syntax highlighting :

Other recommendations are:

• Keep property UpdateMode set to umBackground. It comes set to this value by default, and it's he best setting for most applications anyway.
• Use OnProgress handlers to provide visual indications of loading/saving from/to files. Loading/saving from /to local disk files is usually fast enough to not be a factor. Yet we recommend using an OnProgress handler to provide visual indication of processing if there is a possibility that those files are larger than 5MB. For network files, an OnProgress handler is highly suggested, even for short files.
• If you set the text content programmatically (as opposed to loading it from a file), it is best to use an intermediate temporary file if the amount of text is large. Your text generation code should build a local disk file, which is then loaded in the memo through its LoadFromStream or Lines.LoadFromFile method.