diff --git a/backend/src/api/mining/mining.ts b/backend/src/api/mining/mining.ts
index d3fadbcce..ebf8fd40d 100644
--- a/backend/src/api/mining/mining.ts
+++ b/backend/src/api/mining/mining.ts
@@ -114,31 +114,29 @@ class Mining {
     const poolsStatistics = {};
 
     const poolsInfo: PoolInfo[] = await PoolsRepository.$getPoolsInfo(interval);
-    const emptyBlocks: any[] = await BlocksRepository.$countEmptyBlocks(null, interval);
 
     const poolsStats: PoolStats[] = [];
     let rank = 1;
+    let blockCount = 0;
 
     poolsInfo.forEach((poolInfo: PoolInfo) => {
-      const emptyBlocksCount = emptyBlocks.filter((emptyCount) => emptyCount.poolId === poolInfo.poolId);
       const poolStat: PoolStats = {
         poolId: poolInfo.poolId, // mysql row id
         name: poolInfo.name,
         link: poolInfo.link,
         blockCount: poolInfo.blockCount,
         rank: rank++,
-        emptyBlocks: emptyBlocksCount.length > 0 ? emptyBlocksCount[0]['count'] : 0,
+        emptyBlocks: poolInfo.emptyBlocks,
         slug: poolInfo.slug,
         avgMatchRate: poolInfo.avgMatchRate !== null ? Math.round(100 * poolInfo.avgMatchRate) / 100 : null,
         avgFeeDelta: poolInfo.avgFeeDelta,
         poolUniqueId: poolInfo.poolUniqueId
       };
       poolsStats.push(poolStat);
+      blockCount += poolInfo.blockCount;
     });
 
     poolsStatistics['pools'] = poolsStats;
-
-    const blockCount: number = await BlocksRepository.$blockCount(null, interval);
     poolsStatistics['blockCount'] = blockCount;
 
     const totalBlock24h: number = await BlocksRepository.$blockCount(null, '24h');
@@ -151,6 +149,8 @@ class Mining {
       poolsStatistics['lastEstimatedHashrate1w'] = await bitcoinClient.getNetworkHashPs(totalBlock1w);
     } catch (e) {
       poolsStatistics['lastEstimatedHashrate'] = 0;
+      poolsStatistics['lastEstimatedHashrate3d'] = 0;
+      poolsStatistics['lastEstimatedHashrate1w'] = 0;
       logger.debug('Bitcoin Core is not available, using zeroed value for current hashrate', logger.tags.mining);
     }
 
diff --git a/backend/src/mempool.interfaces.ts b/backend/src/mempool.interfaces.ts
index 24e01d4dd..3f1403518 100644
--- a/backend/src/mempool.interfaces.ts
+++ b/backend/src/mempool.interfaces.ts
@@ -17,6 +17,7 @@ export interface PoolInfo {
   name: string;
   link: string;
   blockCount: number;
+  emptyBlocks: number;
   slug: string;
   avgMatchRate: number | null;
   avgFeeDelta: number | null;
@@ -25,7 +26,6 @@ export interface PoolInfo {
 
 export interface PoolStats extends PoolInfo {
   rank: number;
-  emptyBlocks: number;
 }
 
 export enum TemplateAlgorithm {
diff --git a/backend/src/repositories/BlocksRepository.ts b/backend/src/repositories/BlocksRepository.ts
index faa8fce74..20d0a6e46 100644
--- a/backend/src/repositories/BlocksRepository.ts
+++ b/backend/src/repositories/BlocksRepository.ts
@@ -305,39 +305,6 @@ class BlocksRepository {
     }
   }
 
-  /**
-   * Get empty blocks for one or all pools
-   * @asyncSafe
-   */
-  public async $countEmptyBlocks(poolId: number | null, interval: string | null = null): Promise<any> {
-    interval = Common.getSqlInterval(interval);
-
-    const params: any[] = [];
-    let query = `SELECT count(height) as count, pools.id as poolId
-      FROM blocks
-      JOIN pools on pools.id = blocks.pool_id
-      WHERE tx_count = 1 AND stale = 0`;
-
-    if (poolId) {
-      query += ` AND pool_id = ?`;
-      params.push(poolId);
-    }
-
-    if (interval) {
-      query += ` AND blockTimestamp BETWEEN DATE_SUB(NOW(), INTERVAL ${interval}) AND NOW()`;
-    }
-
-    query += ` GROUP by pools.id`;
-
-    try {
-      const [rows] = await DB.query(query, params);
-      return rows;
-    } catch (e) {
-      logger.err('Cannot count empty blocks. Reason: ' + (e instanceof Error ? e.message : e));
-      throw e;
-    }
-  }
-
   /**
    * Return most recent block height
    * @asyncSafe
@@ -360,17 +327,26 @@ class BlocksRepository {
     interval = Common.getSqlInterval(interval);
 
     const params: any[] = [];
-    let query = `SELECT count(height) as blockCount
-      FROM blocks 
-      WHERE stale = 0`;
-
-    if (poolId) {
-      query += ` AND pool_id = ?`;
+    let query;
+    if (!poolId && !interval) {
+      // optimized query to get full indexed block count
+      query = `SELECT CAST(COALESCE(MAX(height) - MIN(height) + 1, 0) AS SIGNED) as blockCount FROM blocks`;
+    } else if (!poolId) {
+      // optimized query for indexed count within an interval
+      query = `SELECT GREATEST(0, COALESCE(
+        CAST((SELECT height FROM blocks WHERE stale = 0 AND blockTimestamp <= NOW() ORDER BY blockTimestamp DESC LIMIT 1) AS SIGNED) -
+        CAST((SELECT height FROM blocks WHERE stale = 0 AND blockTimestamp >= DATE_SUB(NOW(), INTERVAL ${interval}) ORDER BY blockTimestamp ASC LIMIT 1) AS SIGNED) + 1
+      , 0)) as blockCount`;
+    } else {
+      // for specific pools, we do still have to actually count the blocks
+      query = `SELECT count(*) as blockCount
+        FROM blocks
+        WHERE stale = 0 AND pool_id = ?`;
       params.push(poolId);
-    }
 
-    if (interval) {
-      query += ` AND blockTimestamp BETWEEN DATE_SUB(NOW(), INTERVAL ${interval}) AND NOW()`;
+      if (interval) {
+        query += ` AND blockTimestamp BETWEEN DATE_SUB(NOW(), INTERVAL ${interval}) AND NOW()`;
+      }
     }
 
     try {
diff --git a/backend/src/repositories/PoolsRepository.ts b/backend/src/repositories/PoolsRepository.ts
index fcc218f7b..4fc3742fd 100644
--- a/backend/src/repositories/PoolsRepository.ts
+++ b/backend/src/repositories/PoolsRepository.ts
@@ -38,6 +38,7 @@ class PoolsRepository {
     let query = `
       SELECT
         COUNT(blocks.height) As blockCount,
+          COUNT(CASE WHEN blocks.tx_count = 1 THEN 1 END) AS emptyBlocks,
           pool_id AS poolId,
           pools.name AS name,
           pools.link AS link,
@@ -47,7 +48,7 @@ class PoolsRepository {
           unique_id as poolUniqueId
       FROM blocks
       JOIN pools on pools.id = pool_id
-      LEFT JOIN blocks_audits ON blocks_audits.height = blocks.height
+      LEFT JOIN blocks_audits ON blocks_audits.hash = blocks.hash
       WHERE blocks.stale = 0
     `;