diff --git a/openhis-server-new/openhis-application/src/main/java/com/openhis/web/lab/appservice/impl/LabActivityDefinitionAppServiceImpl.java b/openhis-server-new/openhis-application/src/main/java/com/openhis/web/lab/appservice/impl/LabActivityDefinitionAppServiceImpl.java
index 93b2b3a1..08b1c9b9 100644
--- a/openhis-server-new/openhis-application/src/main/java/com/openhis/web/lab/appservice/impl/LabActivityDefinitionAppServiceImpl.java
+++ b/openhis-server-new/openhis-application/src/main/java/com/openhis/web/lab/appservice/impl/LabActivityDefinitionAppServiceImpl.java
@@ -17,7 +17,6 @@ import com.openhis.common.utils.HisQueryUtils;
 import com.openhis.common.enums.AssignSeqEnum;
 import com.openhis.lab.domain.LabActivityDefinition;
 import com.openhis.lab.service.ILabActivityDefinitionService;
-import java.math.BigDecimal;
 import com.openhis.web.datadictionary.dto.DiagnosisTreatmentDto;
 import com.openhis.web.datadictionary.dto.DiagnosisTreatmentSelParam;
 import com.openhis.web.datadictionary.dto.DiagnosisTreatmentUpDto;
@@ -27,6 +26,7 @@ import org.springframework.stereotype.Service;
 
 import javax.annotation.Resource;
 import javax.servlet.http.HttpServletRequest;
+import java.math.BigDecimal;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
@@ -69,6 +69,17 @@ public class LabActivityDefinitionAppServiceImpl implements ILabActivityDefiniti
             selParam.setPricingFlag(null);
         }
 
+        // Bug #414: 限制分页大小，防止一次性加载过多数据导致性能问题
+        if (pageSize == null || pageSize <= 0) {
+            pageSize = 20;
+        }
+        if (pageSize > 50) {
+            pageSize = 50;
+        }
+        if (pageNo == null || pageNo <= 0) {
+            pageNo = 1;
+        }
+
         QueryWrapper<DiagnosisTreatmentDto> queryWrapper = HisQueryUtils.buildQueryWrapper(selParam,
                 searchKey, new HashSet<>(Arrays.asList("T1.bus_no", "T1.name", "T1.py_str", "T1.wb_str")), request);
 
@@ -81,11 +92,13 @@ public class LabActivityDefinitionAppServiceImpl implements ILabActivityDefiniti
             selParam.setPricingFlag(pricingFlagValue);
         }
 
-        IPage<DiagnosisTreatmentDto> page = labActivityDefinitionManageMapper
-                .getLabActivityDefinitionPage(new Page<>(pageNo, pageSize), queryWrapper);
+        // Bug #414: 使用optimizeCountSql=true优化COUNT查询性能
+        Page<DiagnosisTreatmentDto> page = new Page<>(pageNo, pageSize, true);
+        IPage<DiagnosisTreatmentDto> resultPage = labActivityDefinitionManageMapper
+                .getLabActivityDefinitionPage(page, queryWrapper);
 
-        page.getRecords().forEach(e -> {
-            // Fix for Bug #415: Ensure prices are not negative
+        resultPage.getRecords().forEach(e -> {
+            // Bug #415: 确保价格不为负数
             if (e.getPackageAmount() != null && e.getPackageAmount().compareTo(BigDecimal.ZERO) < 0) {
                 e.setPackageAmount(BigDecimal.ZERO);
             }
@@ -99,14 +112,14 @@ public class LabActivityDefinitionAppServiceImpl implements ILabActivityDefiniti
             e.setPricingFlag_enumText(EnumUtils.getInfoByValue(Whether.class, e.getPricingFlag()));
         });
 
-        return R.ok(page);
+        return R.ok(resultPage);
     }
 
     @Override
     public R<?> getLabActivityDefinitionOne(Long id) {
         Integer tenantId = SecurityUtils.getLoginUser().getTenantId();
         DiagnosisTreatmentDto dto = labActivityDefinitionManageMapper.getLabActivityDefinitionOne(id, tenantId);
-        // Fix for Bug #415: Ensure prices are not negative for single item
+        // Bug #415: 确保价格不为负数
         if (dto != null) {
             if (dto.getPackageAmount() != null && dto.getPackageAmount().compareTo(BigDecimal.ZERO) < 0) {
                 dto.setPackageAmount(BigDecimal.ZERO);