Add information on dashboard refresh rates (#244)

Author: tothmano

dashboards/configure.mdx

@@ -15,6 +15,20 @@ To select the time range:
 1. Choose one of the following options:
     - Use the **Quick range** items to quickly select popular time ranges.
     - Use the **Custom start/end date** fields to select specific times.
+1. Click **Apply**.
+
+## Select refresh rate
+
+Your dashboard regularly queries your data in the background to show the latest trends. The refresh rate is the time interval between these queries.
+
+To select the refresh rate:
+1. In the top right, click <img src="/doc-assets/icons/clock.svg" className="inline-icon" alt="Time range" /> **Time range**.
+1. Select one of the options in **Refresh rate**.
+1. Click **Apply**.
+
+<Warning>
+Each time your dashboard refreshes, it runs a query on your data which results in query costs. Selecting a short refresh rate (such as 15s) for a long time range (such as 90 days) means that your dashboard frequently runs large queries in the background. To optimize query costs, choose a refresh rate that is appropriate for the time range of your dashboard.
+</Warning>
 
 ## Share dashboards
 

reference/query-hours.mdx

@@ -66,6 +66,24 @@ As an example, a typical query analyzing 1 million events might consume approxim
 
 Your GB-hours allowance depends on your pricing plan. To learn more about the plan offerings and find the one that best suits your needs, see [Axiom Pricing](https://axiom.co/pricing).
 
-## Optimize Axiom usage
+## Optimize queries to lower costs
 
-For more information on how to save on query costs, see [Optimize queries](/reference/performance#optimize-queries).
+This section explains ways you can optimize your queries to save on query costs. For more information optimizing your queries for performance, see [Optimize performance](/reference/performance).
+
+### Optimize the order of field-specific filters
+
+Field-specific filters narrow your query results to events where a field has a given value. For example, the APL query `where ["my-field"] == "axiom"` filters for events where the `my-field` field takes the value `axiom`.
+
+Include field-specific filters near the beginning of your query for modest savings in query costs. For more information, see [Poor filter order in queries](/reference/performance#poor-filter-order-in-queries)
+
+### Optimize `search` operator and non-field-specific filters
+
+Non-field-specific filters narrow your query results by searching across multiple datasets and fields for a given value. Examples of non-field-specific filters are the `search` operator and equivalent expressions such as `where * contains` or `where * has`.
+
+Using non-field-specific filters can have a significant impact on query costs. For more information, see [Use the `search` operator efficiently](/apl/tabular-operators/search-operator#use-the-search-operator-efficiently) and [Regular expressions when simple filters suffice](/reference/performance#regular-expressions-when-simple-filters-suffice).
+
+## Optimize dashboard refresh rates
+
+Each time your dashboard refreshes, it runs a query on your data which results in query costs. Selecting a short refresh rate (such as 15s) for a long time range (such as 90 days) means that your dashboard frequently runs large queries in the background.
+
+To optimize query costs, choose a refresh rate that is appropriate for the time range of your dashboard. For more information, see [Select refresh rate](/dashboards/configure#select-refresh-rate).