export type PerfName = "startTime" | "extensionActivated" | "inputLoaded" | "webviewCommLoaded" | "customMarkdownLoaded" | "editorLoaded";
type PerformanceMark = {
    [key in PerfName]?: number;
};
export declare class NotebookPerfMarks {
    private _marks;
    get value(): PerformanceMark;
    mark(name: PerfName): void;
}
export {};